GIFT  OF 

Rheology  Seminar 


EHQiNEERING  LJBRAEY 


STUDIES  ON  SOLUTION  IN  ITS  RELATION  TO  LIGHT 

ABSORPTION,  CONDUCTIVITY,  VISCOSITY, 

AND  HYDROLYSIS 

A  REPORT 

UPON 

A  NUMBER  OF  EXPERIMENTAL  INVESTIGATIONS  CARRIED 

OUT  IN  THE  LABORATORY  OF  THE  LATE 

PROFESSOR  HARRY  C.  JONES 


COMPILED  BY  PAUL  B.  DAVIS 


CARNEGIE  INSTITUTION  OF  WASHINGTON 
1918 


/    r/ 

STUDIES  ON  SOLUTION  IN  ITS  RELATION  TO  LIGHT 

ABSORPTION,  CONDUCTIVITY,  VISCOSITY, 

AND  HYDROLYSIS 

,  ^,       t-.v     •     A  REPORT 

UPON 

A  NUMBER  OF  EXPERIMENTAL  INVESTIGATIONS  CARRIED 

OUT  IN  THE  LABORATORY  OF  THE  LATE 

PROFESSOR  HARRY  C.  JONES 


COMPILED  BY  PAUL  B.  DAVIS 


CARNEGIE  INSTITUTION  OP  WASHINGTON 
1918 


CARNEGIE  INSTITUTION  OF  WASHINGTON 
PUBLICATION  No.  260 


!.!3RA«f 


PRESS   OF   GIBSON   BROTHERS 
WASHINGTON,  D.  C. 


PREFACE. 

The  several  chapters  comprising  this  report  represent  the  various 
lines  of  investigation  pursued  under  the  direction  of  the  late  Professor 
Harry  C.  Jones  during  the  year  1915-16  and  hi  the  case  of  the  work 
of  Davis  and  Johnson  continued  in  1916-17.  Although  somewhat 
diverse  in  nature,  they  all  bear  directly  or  indirectly  upon  the  concep- 
tions of  solution  in  general  and  of  solvation  in  particular  which  have 
been  developed  in  this  laboratory  during  the  past  fifteen  years. 

Dr.  Hulburt  and  Dr.  Hutchinson  have  measured  the  absorption 
coefficient  of  solutions  of  a  number  of  salts  in  differents  solvents  for 
monochromatic  radiation.  They  have  calculated  from  this  the  molec- 
ular absorption  coefficient  for  such  solutions  and  have  made  a  careful 
comparative  study  of  the  molecular  absorption-concentration  curves. 

The  investigation  of  formamid  as  a  solvent,  begun  by  Davis  and 
Putnam,  has  been  continued  by  Dr.  Davis  and  Dr.  Johnson.  In  addi- 
tion to  observing  the  behavior  of  a  series  of  nitrates  and  formates  in 
this  solvent,  they  have  determined  the  conductivity  and  viscosity  of 
solutions  of  a  number  of  salts  of  the  organic  acids  and  have  also  studied 
several  representative  salts  in  mixtures  of  formamid  with  ethyl  alcohol. 

Dr.  Davis  has  also  made  some  observations  on  the  viscosity  of 
csesium  salts  hi  binary  mixtures  of  glycerol  and  of  formamid  with  water. 

Dr.  Lloyd  and  Dr.  Pardee  have  extended  the  work  in  absolute  ethyl 
alcohol  to  include  a  study  of  the  conductivities  of  the  sodium  salts  of  a 
number  of  organic  acids  and  have  succeeded  in  applying  the  formula  of 
Noyes  and  Johnston  for  aqueous  solutions  to  the  calculation  of  disso- 
ciation in  this  solvent. 

Dr.  Ordeman  has  completed  his  study  of  the  relative  dissociating 
power  of  free  and  combined  water  reported  on  in  part  in  Publication 
No.  230  of  the  Carnegie  Institution  of  Washington. 

Dr.  Connolly  has  investigated  the  different  chemical  activity  of  free 
and  semi-combined  water,  using  as  an  illustration  the  effect  of  neutral 
salts  in  the  hydrolysis  of  acetic  anhydride.  A  preliminary  paper  on 
this  work  is  also  to  be  found  in  Publication  No.  230. 

The  results  of  all  these  investigations,  which  have  been  carried  out 
with  aid  of  generous  grants  from  the  Carnegie  Institution  of  Washing- 
ton, are  recorded  in  this  volume.  The  writer  also  wishes  to  thank 
that  Institution  for  making  possible  the  completion  of  certain  investi- 
gations left  unfinished  by  the  untimely  death  of  Professor  Jones,  and 
the  Chemical  Staff  of  this  University  for  their  courtesy  in  extending 
the  facilities  of  the  laboratory. 

PAUL  B.  DAVIS. 

THE  JOHNS  HOPKINS  UNIVERSITY,  June  1917. 

i 


912121 


// 


. 


*  lAtoiftlafti  al*  )- 


CONTENTS. 
CHAPTER  I. 

THE  ABSORPTION  COEFFICIENT  OF  SOLUTION  FOR  MONO-CHROMATIC  RADIATION: 

PAGE. 

Introduction 6 

Statement  of  the  problem 9 

Historical 

Apparatus 12 

Procedure . . 14 

Sut    Errors  and  corrections 17 

THE  ABSORPTION  COEFFICIENT  OF  THE  SOLVENTS: 

Water 18 

Methyl  alcohol 20 

Ethyl  alcohol 21 

Propyl  alcohol 21 

Iso-butyl  alcohol 21 

Iso-amyl  alcohol 21 

Discussion  of  results  with  the  solvents 21 

THE  ABSORPTION  COEFFICIENT  OF  THE  SOLUTIONS: 

Cobalt  chloride  in  water 23 

Cobalt  chloride  in  methyl  alcohol 26 

Cobalt  chloride  in  ethyl  alcohol 29 

Cobalt  chloride  in  propyl  alcohol 31 

Cobalt  chloride  in  iso-butyl  alcohol 32 

Cobalt  chloride  in  iso-amyl  alcohol 33 

Discussion  of  results  for  cobalt  chloride 35 

Cobalt  chloride  in  methyl  alcohol  with  water 36 

Cobalt  chloride  in  ethyl  alcohol  with  water 37 

Cobalt  chloride  in  propyl  alcohol  with  water 40 

Cobalt  nitrate  in  water 40 

Cobalt  sulphate  in  water . .  43 

Nickel  chloride  in  water. 47 

Hydrated  nickel  chloride  in  the  alcohols 51 

Nickel  nitrate  in  water 54 

Nickel  sulphate  in  water 59 

Ferric  ammonium  sulphate  in  water 62 

Chromium  chloride  in  water 64 

Chromium  nitrate  in  water 66 

Chromium  sulphate  in  water 67 

Potassium  permanganate  in  water 67 

Conclusion , 69 

CHAPTER  II. 

THE  CONDUCTIVITY  AND  VISCOSITY  OF  CERTAIN  ORGANIC  AND  INORGANIC  SALTS 

IN    FORMAMID    AND    IN    MIXTURES   OF   FORMAMID   WITH  ETHYL  ALCOHOL: 

Introduction 71 

Experimental 72 

Preparation  of  the  solvents 72 

Preparation  of  the  salts 73 

Preparation  of  the  solutions 73 

Apparatus 73 

Procedure 75 

3 


4  Contents. 

Tables:  PAGE. 

Ammonium  nitrate  in  f ormamid 76 

Potassium  nitrate  in  f  ormamid 

Sodium  nitrate  in  formamid 77 

Calcium  nitrate,  barium  nitrate ......; 

Strontium  nitrate 79 

Rubidium  formate 79 

Ammonium  formate 80 

Sodium  formate 80 

Lithium  formate 81 

Barium  formate 81 

Strontium  formate 82 

Sodium  benzoate 82 

Sodium  metabrombenzoate 83 

Sodium  metamido  benzoate 83 

Sodium  dinitro  benzoate /!**  ~  84 

Sodium  salicylate lv i* : 7  84 

Sodium  benzene  sulpbonate 85 

Sodium  succinate L *.J?t  85 

Tetraethylammonium  iodide  in  formamid  with  alcohol 86 

Rubidium  iodide  in  formamid  with  alcohol 87 

Lithium  nitrate  in  formamid  with  alcohol 89 

Calcium  nitrate  in  formamid  with  alcohol 90 

Discussion  of  results 91 

CHAPTER  III. 

A  NOTE  ON  THE  VISCOSITY  OF  CESIUM  SALTS  IN  GLYCEROL- WATER  MIXTURES: 

Caesium  chloride 97 

Caesium  nitrate 98 

CHAPTER  IV. 

A  STUDY  OP  THE  ELECTRICAL  CONDUCTANCE  OP  THE  SODIUM  SALTS  OF  CERTAIN 
ORGANIC  ACIDS  IN  ABSOLUTE  ETHYL  ALCOHOL  AT  15°,  25°,  AND  35°: 

Introduction 99 

Historical 99 

Experimental 103 

Reagents 103 

Apparatus 105 

Procedure 106 

Measurements: 

Explanation  of  tables 109 

Sodium  formate  and  acetate 109 

Sodium  monochloro,  dichloro,  trichloro,  and  phenyl  acetates:   propionate 

and  ido-propionate;  butyrate  and  oxy  isobutyrate 110 

Sodium  benzoate;  ortho  amido  and  p-amido  benzoates,  m-  and  p-bromben- 

zoates;  o-,  m-,  and  p-chlorobenzoates Ill 

Soduim  salicylate;  m-andp-hydroxybenzoates;  acetyl,  iodo  and  sulphosalicyl- 

ates;  o-  and  meta  nitrobenzoates 112 

Sodium  p-nitro  and  2.4  dinitro  ben/oates,  ortho,  meta,  and  paratoluates  and 

picrate 113 

Discussion  of  results 

Summary 118 


Contents.  5 
CHAPTER  V. 

A  STUDY  OF  THE  DISSOCIATING  POWER  OP  FREE  AND  OP  COMBINED  WATER  :  PAGE. 

Introduction 119 

Experimental 119 

Apparatus 119 

Solvents 121 

Salts 122 

Solutions 123 

Procedure 124 

Measurements 125 

Tables 125-127 

Discussion  of  results 127 

CHAPTER  VI. 

THE  DIFFERENCE  IN  CHEMICAL  ACTIVITY  OF  FREE  AND  SEMI-COMBINED  WATER 
AS  ILLUSTRATED  BY  THE  EFFECT  OF  NEUTRAL  SALTS  ON  THE  HYDROLYSIS 
OF  ACETIC  ANHYDRIDE: 

Hydrolysis 131 

Hydrotysis  of  acetic  anhydride 131 

Hydrolysis  of  salts 134 

Neutral  salt  action 134 

Effect  of  neutral  salts  on  catalytic  activity  of  acids 135 

Effect  of  neutral  salts  on  hydrolysis  by  water  alone 135 

Statement  of  the  problem 137 

Experimental: 

Purification  of  acetic  anhydride 137 

Purification  of  salts 138 

Apparatus 138 

Solutions 138 

Method  of  procedure 139 

Calculations 140 

Data 140-143 

Discussion  of  results 143 


STUDIES  ON  SOLUTION  IN  ITS  RELATION  TO  LIGHT 

ABSORPTION,  CONDUCTIVITY,  VISCOSITY, 

AND  HYDROLYSIS 


A  REPORT  UPON  A  NUMBER  OF  EXPERIMENTAL  INVESTIGA- 
TIONS CARRIED  OUT  IN  THE  LABORATORY  OF  THE 
LATE  PROFESSOR  HARRY  C.  JONES 


Compiled  by  PAUL  B.  DAVIS 


CHAPTER  I. 

THE  ABSORPTION  COEFFICIENT  OF  SOLUTION  FOR  MONOCHROMATIC 

RADIATION. 


BY   E.    O.    HULBURT   AND   J.    F.    HUTCHINSON. 


INTRODUCTION. 
STATEMENT  OF  THE  PROBLEM. 

Experiments  have  shown  that  in  the  case  of  certain  solutions  the 
absorption  of  monochromatic  radiation  may  be  represented  by  the 
formula 

7  =  /0XlO— '  (1) 

where  70  is  the  original  intensity  of  the  radiation,  I  is  the  intensity  of 
the  radiation  after  passing  through  a  layer  of  solution  of  thickness  t 
millimeters,  and  a  is  a  quantity,  called  the  absorption  coefficient  of  the 
solution  for  the  specified  frequency  of  radiation. 

Experiments  have  also  shown  that  different  values  of  a  are  obtained 
if  there  is  any  change  in: 

(a)  the  nature  of  the  solvent  or  of  the  dissolved  substance. 
(6)  the  concentration  of  the  solution. 

(c)  the  temperature. 

(d)  the  wave-length  of  the  radiation,  etc. 

To  solve  the  problem  of  light-absorption  in  solutions  it  is  necessary 
to  determine  the  explicit  form  of  the  relation  between  the  absorption 
coefficient  a  and  the  quantities  of  which  it  is  a  function.  At  present 
our  knowledge  is  far  too  meager  to  indicate  more  than  a  qualitative  idea 
of  the  nature  of  this  relation. 

In  the  present  investigation  a  has  been  measured  in  those  regions  of 
the  spectrum  where  the  pure  solvents  possess  appreciable  absorption. 
It  is  assumed  that  the  total  absorption  of  the  solution  is  the  sum  of 
two  parts,  the  first  being  the  absorption  due  to  the  presence  of  the  salt, 
the  second  being  the  absorption  due  to  the  pure  solvent.  In  calcu- 
lating this  second  part,  it  is  assumed  that  the  absorption  due  to  the 
solvent  is  the  same  as  it  would  be  if  there  were  no  dissolved  salt  present. 
We  therefore  write 


10  Studies  on  Solution. 

where  a0is  the  absorption  coefficient  for  the  pure  solvent,  c  is  the  concen- 
tration in  gram-molecules  of  salt  per  liter  of  solution,  and  A  is  called  the 
molecular  absorption  coefficient  of  the  salt  in  the  solution.  From  this 
relation  it  follows  that 


The  present  investigation  has  consisted  of  a  systematic  and  thorough 
study  of  the  absorption  coefficient  a.  This  quantity  has  been  measured 
at  intervals  of  20juju  to  40/iM  throughout  the  region  of  the  spectrum  from 
600/z/*  to  l,300ju/z  for  many  solutions.  The  work  has  been  restricted  to 
a  study  of  inorganic  salts  in  aqueous  and  alcoholic  solution.  All  the 
measurements  have  been  carried  out  with  solutions  at  room  tempera- 
ture. The  values  of  a,  when  plotted  as  ordinates  against  the  corre- 
sponding wave-lengths  as  abscissas,  form  the  absorption  curve.  For 
each  salt  a  series  of  solutions  varying  in  concentration  from  satura- 
tion to  moderate  dilution  was  prepared  and  the  absorption  curve  has 
been  drawn  for  each  solution.  From  the  measured  values  of  a  and  OQ 
and  from  the  known  value  of  c,  A  has  been  calculated  for  each  wave- 
length by  means  of  formula  (2).  The  values  of  A  for  a  given  wave- 
length have  been  plotted  as  ordinates  against  the  corresponding  values 
of  c  as  abscissas.  The  curves  thus  formed  will  be  referred  to  as  the 
A-c  curves.  It  was  the  purpose  of  the  present  investigation  to  deter- 
mine the  form  of  the  A-c  curves. 

HISTORICAL. 

The  general  problem  of  the  absorption  of  radiation  by  solutions  has 
been  the  subject  of  many  investigations.  Only  those  papers  are  of 
primary  interest  here  which  concern  determinations  of  the  numerical 
values  of  the  absorption  coefficient  as  a  function  of  the  concentration. 

Beer1  measured  the  absorption  coefficient  for  red  light  of  a  number  of 
aqueous  solutions  of  inorganic  salts.  The  results  of  his  experiments 
showed  that  within  the  error  of  experiment  A  was  a  constant  with 
respect  to  c.  The  statement  that  "A  is  a  constant"  has  been  men- 
tioned by  subsequent  workers  in  this  field  as  ''Beer's  law."  This 
"law"  has  since  been  shown  to  be  the  exception  rather  than  the  rule, 
and  therefore  in  this  paper  but  few  references  have  been  made  to 
"Beer's  law." 

A  paper  by  Rudorf2  entitled  "  Lichtabsorption  in  Losungen  vom 
Standpunkt  der  Dissociationstheorie"  reviews  the  literature  up  to  the 
year  1904  and  gives  a  very  good  statement  of  the  conclusions  reached 
at  that  time.  Rudorf  concluded  the  section  of  his  paper  concerning 
Beer's  law  with  the  following  observation: 

lPogg.  Ann.,  86,  78  (1882). 

'Sammlung  Chemischer  und  Chemish-Technischer  Vortrage,  9,  1  (1904). 


The  Absorption  Coefficient  of  Solution  for  Monochromatic  Radiation.      11 

"We  have  seen  that  in  general  Beer's  law  can  be  true  only  within  certain 
limits,  though  many  observers  believe  that  it  holds  accurately  within  wide 
limits.  The  experimental  data  is  in  many  cases  unsatisfactory,  and  in  still 
others  contradictory." 

A  survey  of  the  literature  since  1904  bearing  on  the  relation  between 
A  and  c  yields  few  definite  conclusions.  The  reason  for  the  unsettled 
state  of  the  problem  is  not  difficult  to  find.  None  of  the  researches 
has  been  carried  out  with  the  necessary  completeness.  The  investi- 
gators have  been  content  with  a  determination  of  the  molecular  absorp- 
tion coefficient  A  for  a  few  concentrations  at  a  very  limited  number  of 
points  of  the  spectrum. 

In  1906  Miiller1  measured  A  for  three  solutions  of  copper  chloride  in 
water.  The  values  of  A  were  determined  for  5  wave-lengths  in  that  part 
of  the  visible  region  of  the  spectrum  where  this  solution  was  fairly  trans- 
parent, Muller's  results  snowed  that  A  was  not  only  variable  with  c, 
but  also  that  the  rate  of  variation  was  different  for  each  wave-length. 

Hantzsch?  and  his  co-workers  (the  reference  is  to  the  final  one  of  a 
series  of  papers)  have  recorded  the  value  of  A  for  a  number  of  solutions 
of  inorganic  colored  salts.  A  was  measured  for  a  single  wave-length 
for  a  few  concentrations  and  was  found  in  general  to  decrease  with  cin 
the  ease  of  the  monochromates,  the  ferrocyanides,  and  the  permangan- 
ates of  the  alkali  metals,  and  to  be  fairly  constant  for  dilute  solutions 
of  certain  organic  colored  salts.  .  , 

Sheppard,3  in  his  researches,  has  included  determinations  of  A  for 
alcoholic  solutions  of  a  few  dyes.  The  values  of  A  were  constant 
within  the;  error  of  experiment,  except  for  the  most  dilute  solutions, 
where  they  experienced  a  perceptible  increase,  which  was  ascribed  to 
chemical  change  taking  place  in  the  solution. 

Garrett4  has  recorded  the  values,  of  A  for  aqueous  solutions  of  a  num- 
ber of  salts  of  copper.  A  was  determined  for  3  wave-lengths  on  the 
violet  side  of  the  red  absorption  band  for  3  concentrations  and  was 
found  in  all  cases  to  decrease  with  dilution. 

In  the  work  thus  far  cited  the  values  of  A  have  been  determined  for 
wave-lengths  lying  in  the  visible  region  of  the  spectrum  by  means  of  a 
visual  spectro-photometer. 

The  photographic  method  of  testing  Beer's  law,  as  used  by  previous 
workers  in  this  laboratory,5  is  applicable  to  both  the  ultra-violet  and 
visible  regions  of  the  spectrum.  This  method,  however,  yields  informa- 
tion concerning  the  variations  of  A  with  c  only  for  those  wave-lengths 
on  the  edge  of  an  absorption  band.  In  studying  a  large  number  of 
solutions  in  this  way,  many  bands  were  found  whose  edges  obeyed 
Beer's  law  and  many  more  whose  edges  did  not. 

'Ann.  d.  Phys.,  21,  515  (1906).  4Zeit.  Elektrochein.,  19,  1  (1913). 

«Zeit.  phys.  chem.,  84,  321  (1913).  6Carnegie  Inst.  Wash.  Pub.  Nos.  110,  130,  160,  190. 

•Journ.  Chem.  Soc.,  95,  15  (1909);  Proc.  Roy.  Soc.,  82-A,  256  (1909). 


12  Studies  on  Solution. 

A  very  important  quantitative  study  of  the  light-absorption  of  solu- 
tions has  been  carried  out  by  Houstoun  and  his  co-workers1  (the  refer- 
ence is  to  the  last  of  a  series  of  eleven  papers) .  Many  phases  of  the  gen- 
eral problem  were  considered  and  frequent  reference  will  be  made  here 
to  the  separate  papers.  His  work  is  unique  in  that  it  is  the  only  record 
we  have  of  the  determination  of  A  for  solutions  for  wave-lengths  in  the 
infra-red.  Even  this  work,  although  of  a  more  complete  character 
than  any  of  the  researches  hitherto  attempted,  did  little  more  than 
touch  upon  the  relation  between  A  and  c.  The  absorption  curves 
were  determined  for  the  region  of  the  spectrum  from  645/zju  to  1,270/A/x 
for  the  chloride,  bromide,  iodide,  nitrate,  and  sulphate  of  cobalt.2  This 
was  done  for  a  strong  and  for  a  dilute  aqueous  solution  of  each  salt, 
in  all  cases  the  values  of  A  for  the  more  concentrated  solution  were  found 
to  be  greater  than  the  corresponding  values  for  the  dilute  solution. 

Houstoun  also  made  a  further  study  of  the  chloride  and  bromide  of 
cobalt,  nickel,  iron,  and  copper.3  Solutions  of  each  salt  were  prepared 
varying  in  concentration  from  saturation  to  moderate  dilution.  A  was 
determined  for  a  single  wave-length  lying  on  the  edge 
of  an  absorption  band.  The  results  for  nickel  chlo-  TABLE  i.— Nickel 
ride  as  an  example  are  given  in  table  1.  The  values  Chloride  in  Water. 
of  A  are  seen  to  decrease  with  dilution  reaching  a  Wave-length  434/1/1. 
minimum  value,  and  then  to  remain  fairly  constant. 
Table  1  and  other  similar  tables  show  that  A  increased 
again  for  the  more  dilute  solutions.  This  increase  was 
considered  either  as  within  the  error  of  experiment  or 
due  to  the  chemical  change  taking  place  in  the  solution. 

In  all  of  Houstoun's  work  A  was  determined  by 
comparing  a  cell  containing  the  solution  with  a  cell  of 
the  same  thickness  containing  the  pure  solvent.  This 
method  is  open  to  criticism,  but  the  difference  be- 
tween the  A  thus  determined  and  the  true  value  was  probably  less 
than  the  errors  in  the  values  of  A  due  to  other  experimental  causes. 

APPARATUS. 

The  apparatus  used  for  determining  the  coefficient  of  light-absorp- 
tion has  been  developed  by  previous  workers  in  the  Johns  Hopkins 
laboratory.  The  quantitative  work  was  begun  by  Guy,4  who  built  a 
sensitive  radiomicrometer  and  used  this  in  connection  with  a  glass- 
prism  spectrograph.  The  apparatus  was  greatly  improved  by  Shaeffer5 
during  the  following  year,  and  the  apparatus  used  in  the  present  inves- 
tigation and  described  in  this  paper  is  the  same  in  all  respects,  except 
for  minor  details,  as  that  used  by  Shaeffer  and  his  co-workers. 

^oc.  Roy.  Soc.  Edinburgh,  33, 156(1912-13).  »/Kd.,31,521  (1910-11).  3/bw*.,33, 147(1912-13). 
'Carnegie  Inst.  Wash.  Pub.  No.  190,  29  (1913).  */Kd.,  230,  44  (1915). 


The  Absorption  Coefficient  of  Solution  for  Monochromatic  Radiation.      13 


The  arrangement  of  the  apparatus  is  shown  in  figure  1.  The  light 
from  a  Nernst  glower  g,  operated  at  110  volts  on  0.8-ampere  direct 
current  from  a  constant  potential  storage  battery,  was  rendered 
parallel  by  a  lens  Zi,  3.8  cm.  in  diameter  and  with  a  focal  length  of 
20  cm.  The  light  after  passing  through  cell  K'  was  focussed  on  the  slit 
A  of  the  spectrograph  by  a  second  lens  k,  3.8  cm.  in  diameter  and  with 
a  focal  length  of  20  cm.  A  shutter  s  was  placed  between  the  glower  g 
and  lens  /i,  by  means  of  which  the  light  could  be  turned  on  and  off. 

The  optical  system  thus  far  described,  con- 
sisting of  the  glower,  the  two  lenses  Zi  and  Z2, 
and  the  cells,  was  held  by  a  solid  metal  frame- 
work and  was  perpendicular  to  the  plane  of  the 
drawing  in  figure  1.  The  light  after  passing 
through  lens  Z2  was  reflected  onto  slit  A  by  a 
right-angle  glass  prism  (not  shown  in  figure  1) 
close  to  slit  A. 

The  temperature  of  the 
solution  was  recorded  by  a 
thermometer  not  placed  in 
the  solution  but  fastened  on 
the  metal  frame  supporting 
the  cells. 

The    spectrograph    con- 
sisted of  the  Littrow  mount- 
ing of  a  plane  grating.  The 
grating  had  a  ruled  area  6  cm.  by  7.5  cm.  and 
was  ruled  15,000  lines  to  the  inch.    The  cone 
of  light  from  slit  A  was  reflected  by  a  right- 
angle  glass  prism  through  the  large  achromatic 
lens  Z3,  10  cm.  in  diameter  and  with  a  focal 
length  of  75  cm.     The  spectrum  was  brought 
to  a  focus  at  slit  B.    The  grating  possessed  a 
bright  first-order,  and  this  first-order  spectrum 
FIG.  i.— Schematic  diagram  was  used  throughout  the  present  work.    The 

dispersion  was  such  that  with  slit  B  1  mm. 
wide  a  beam  of  light  containing  a  wave-length  range  of  20  A.  or  2ju/i 
passed  through.  In  this  work  both  slit  A  and  slit  B  were  always  1 
mm.  in  width.  The  grating  was  mounted  on  a  turntable,  which  was 
rotated  from  the  outside  by  a  worm-screw,  thus  causing  various  wave- 
lengths to  pass  through  slit  B.  The  approximately  monochromatic  beam 
of  light  from  slit  B  was  focussed  on  the  junction  of  the  radiomicrometer 
r  by  a  lens  Z4,  3.5  cm.  in  diameter  and  with  a  focal  length  of  6  cm. 

A  complete  description  of  the  construction  of  the  radiomicrometer  is 
given  in  Shaeffer's  paper.1  To  eliminate  the  drift  of  the  zero-point 

Carnegie  Inst.  Wash.  Pub.  No.  230,  p.  44. 


14  Studies  on  Solution. 

of  the  instrument,  due  to  temperature  changes  in  the  air  of  the 
room,  it  was  encased  hi  a  large  box  surrounded  with  an  excelsior 
packing.  When  the  room  temperature  was  kept  fairly  constant,  the 
drift  was  negligible.  Occasionally  readings  were  taken  in  the  presence 
of  a  slight  drift,  and  in  this  case  the  zero  was  redetermined  after  each 
deflection  and  one-half  the  drift  added  to  the  observed  deflection. 
The  deflections  of  the  radiomicrometer  were  observed  on  a  ground- 
glass  scale  at  a  distance  of  5  meters.  This  scale  was  placed  on  the 
table  on  which  was  mounted  the  Nernst  glower  and  cells.  This 
arrangement  enabled  a  single  observer  to  carry  out  all  the  measure- 
ments, i.  e.,  to  manipulate  the  cells,  to  watch  the  glower  current,  and 
to  read  the  deflections. 

The  cells,  which  were  made  by  Shaeffer1  and  described  in  his  paper, 
were  used  in  the  present  work  on  a  few  salts  only.  These  cells,  which 
were  of  brass,  gold-plated,  and  of  adjustable  depth,  although  perfectly 
workable,  were  found  to  be  somewhat  clumsy  for  this  investiga- 
tion. A  cell  was  required  which  could  be  easily  and  quickly  opened, 
cleaned,  and  filled.  The  form  of  cell  finally  chosen  was  very  satis- 
factory. This  cell  (fig.  2)  consisted  simply  of  a  glass  ring,  4.2  cm.  in 
diameter,  closed  on  each  end  by  a  plane-par- 
allel plate  of  glass  2  mm.  thick.  The  glass 


ring  was  ground  to  a  uniform  thickness  within 


4.acms.        *-* 


0.001  inch.1:  It  was  found  unnecessary  to  FlG.2.— Cross-section  of  cell. 
cement  the  glass  plates  on  the  glass  ring. 

To  fill  the  cell  the  glass  ring  was  placed  on  the  bottom  plate,  the 
solutions  poured  in,  and  the  upper  plate  slid  on.  In  the  case  of 
water  solutions,  the  cell  thus  filled  Was  quite  tight  and  remained 
free  from  bubbles  for  several  hours;  in  the  case  of  solutions  of  methyl 
alcohol  small  bubbles  appeared  in  about  half  an  hour.  It  was  some- 
times convenient  to  seal  the  bottom  plate  on  to  the  glass  ring  with 
rubber  cement.  Six  cells  were  made  varying  in  thickness  from  1.844 
to  21.996  mm.  A  thick  cell  K'  and  a  thin  cell  K  (fig.  1),  were  held 
in  a  frame  (not  shown  hi  fig.  1)  and  either  in  turn  could  be  quickly 
interposed  in  the  path  of  the  light. 

PROCEDURE. 

The  solution  for  which  a  was  to  be  determined  was  placed  in  two 
cells  exactly  alike,  except  that  one  was  thin  and  the  other  thick.  The 
energy  /  of  the  monochromatic  beam  of  light  after  passing  through 
the  thin  cell  containing  a  thickness  h  of  solution,  and  the  energy  /' 
after  passing  through  the  thick  cell  containing  a  thickness  h'  of  solution, 
were  measured  in  arbitrary  units — i.  e.,  deflections  of  the  radiomicrom- 

*Camegie  Inst.  Wash.  Pub.  No.  230,  p.  50. 


The  Absorption  Coefficient  of  Solution  for  Monochromatic  Radiation.      15 

eter.  If  the  initial  intensity,  70,  of  the  light  falling  on  the  cell  was  the 
same  in  each  case: 

h  — h     5  I 

a=7logl°3~' 

where  d  and  df  are  the  deflections  produced  by  /  and  I',  respectively, 
and  t  is  the  difference  in  thickness  in  millimeters  of  the  two  cells. 
This  method  eliminated  all  corrections  for  reflections  from  the  glass 
surfaces  and  thus  gave  a  directly. 

For  the  study  of  each  salt,  solutions  of  the  salt  in  the  solvent  were 
prepared  varying  in  concentration  from  saturation  to  moderate  dilution. 
The  absorption  curve  for  each  solution  was  then  drawn.  This  involved 
the  determination  of  a  at  intervals  of  20^  to  40ju/*  throughout  the 
available  region  of  the  spectrum — i.  e.,  from  600/x/z  to  1,300/iju. 

The  experimental  procedure  was  as  follows:  The  two  cells,  filled 
with  the  solution  whose  absorption  was  to  be  measured,  were  mounted 
in  place  in  their  frame  and  were  adjusted  until  the  image  of  the  Nernst 
glower  on  slit  A  suffered  no  displacement  when  either  cell  was  inter- 
posed in  the  path  of  the  light.  The  zero-reading  of  the  radiomicrom- 
eter  was  taken,  and  then  the  deflections  were  noted  for  each  cell  in 
turn  in  the  path  of  the  light.  This  was  done  for  each  wave-length, 
the  shutter  (s,  fig.  1)  being  closed,  usually  after  every  four  readings, 
to  see  if  the  zero  remained  unchanged.  Readings  were  taken  fo? 
wkve-length  intervals  of  20ju/x  to  40juM  throughout  the  entire  available 
spectrum,  and  the  whole  set  was  repeated  in  reverse  order.  Thus; 
each  point  on  an  absorption  curve,  i.  e.,  each  measurement  of  #,  was 
the  mean  of  two,  and  often  more,  separate  determinations. 

As  an  illustration  of  the  method  of  procedure,  the  complete  read- 
ings for  a  solution  of  NiSO4  in  water  are  given  in  table  2. 

The  data  from  which  the  curves  have  been  plotted  are  arranged  iri 
tables.  For  each  solution  the  following  data  are  recorded  in  these 
tables:  the  temperature  of  the  solution  in  degrees  centigrade;  t,  the. 
difference  in  thickness  of  the  two  cells;  c,  the  concentration  in  granv 
molecules  of  salt  per  liter  of  solution;  the  values  of  a  calculated  from 
equation  (3);  and  the  values  of  A  calculated  from  equation  (2). 

The  short-wave  limit  of  the  absorption  curves  is  at  about  600/xju 
because  the  deflections  of  the  radiomicrometer  for  light  of  wave-length 
shorter  than  600/z/i  are  too  small  to  give  accurate  values  of  a.  The 
long-wave  limit  is  at  about  1,200/i/v  although  the  limit  set  by  the 
transparency  of  glass  is  at  about  2,OOOjuM-  The  reason  for  this  was  that 
in  order  to  study  regions  beyond  1,200/iju  a  color  screen  had  to  be  used. 
Wave-length  l,200juM  in  the  first-order is  overlapped  by  wave-length 
of  the  second-order.  A  thin  layer  of  a  strong  solution  of  cnro- 


16 


Studies  on  Solution. 


mium  chloride  in  water  served  as  a  color  screen,  and  such  a  screen  was 
used  whenever  a  was  determined  for  wave-lengths  greater  than  1,200/z/*. 
This  absorbs  the  light  up  to  700juju  (see  fig.  24)  and  is  transparent  for 
wave-lengths  above  this.  Water  itself  is  quite  opaque  above  1,300/i/z 
(see  fig.  3)  and  hence  this  screen  cut  down  the  deflections  to  such  an 
extent  that  the  values  for  a  were  liable  to  great  inaccuracy.  In  most 
cases,  therefore,  the  long-wave  limit  of  the  absorption  curves  is  at 
about  1,200MM- 

TABLE  2.— Nickel  Sulphate  in  Water. 
Temperature  18.6°.         /  =  10mm.         c=0.4. 


Deflections  of  radiomicrometer  ,  in 

millimeters. 

Wave-length. 

Cell  of  thickness 

Cell  of  thickness 

d/d' 

djd' 

a 

=  11  mm. 

=  1  mm. 

d' 

d 

Mean. 

645wi 

30        30 

37        37 

1.25      1.25 

1.25 

0.0097 

866 

38        38 

49        50 

1.29       1.31 

1.30 

0.0114 

585 

38        38    38 

59        63    59 

1.55       1.66  1.55 

1.60 

0.0204 

605 

34        35 

71        74 

2.08      2.10 

2.09 

0.0320 

625 

25        25 

82        77 

3.28      3.08 

3.18 

0.0502 

644 

17         17 

89         89 

5.22      4.94 

5.09 

0.0707 

664 

19        17 

110        95 

5.80      5.60 

5.70 

0.0756 

684 

21         19 

131       110 

6.22      5.80 

6.01 

0.0779 

704 

20        19 

142       127 

7.10      6.68 

6.89 

0.0838 

724 

20        21 

156       140 

7.80      6.67 

7.23 

0.0859 

744 

26        27 

171       168 

6.58      6.22 

6.40 

0.0806 

764 

41        43 

188       186 

4.58      4.33 

4.45 

0.0648 

783 

55        63 

178      198 

3.24      3.15 

3.20 

0.0505 

803 

81        91 

192       212 

2.37      2.33 

2.35 

0.0371 

823 

110      117 

207       221 

1.88         .89 

1.89 

0.0277 

842 

130      141 

215      230 

1.66         .63 

1.65 

0.0218 

861 

151       158 

223       234 

.48         .48 

1.48 

0.0170 

881 

158       165 

227       236 

.44         .43 

1.44 

0.0158 

901 

159       158 

232       229 

.46         .45 

1.46 

0.0164 

920 

149       149 

233       228 

.57         .53 

1.55 

0.0190 

940 

129       123 

232       222 

.80         .81 

1.81 

0.0258 

960 

85        86 

221       214 

2.60      2.49 

2.55 

0.0407 

979 

74        78 

222      233 

3.00      2.98 

2.99 

0.0476 

998 

63         70 

216      229 

3.43       3.26 

3.34 

0.0524 

1018 

61         58 

220      212 

3.61       3.64 

3.63 

0.0560 

1037 

52        53 

211       207 

4.06      3.90 

3.98 

0.0600 

1056 

41         43 

185       196 

4.51       4.56 

4.53 

0.0656 

1076 

33         37 

177       190 

5.36      5.13 

5.24 

0.0719 

1095 

28        27 

173       177 

6.18      6.56 

6.37 

0.0804 

1115 

23        24 

168       167 

7.30      6.96 

7.13 

0.0853 

Kahlbaum  materials  were  used,  and  when  possible  the  salts  were 
purified  by  recrystallization.  In  preparing  the  solutions  a  uniform 
method  was  adopted.  A  solution  saturated  at  room  temperature  was 
prepared,  and  the  concentration  was  determined  by  a  standard  method. 
The  solutions  of  lower  concentration  were  then  prepared  by  diluting 
this  mother  solution. 


The  Absorption  Coefficient  of  Solution  for  Monochromatic  Radiation.      17 
ERRORS  AND  CORRECTIONS. 

The  values  of  a  and  of  A  have  been  plotted  against  wave-length  and 
concentration  respectively.  It  was  thought  better  to  connect  the 
plotted  points  by  straight  lines  rather  than  to  draw  smooth  curves 
through  them.  A  glance  at  the  figures  shows  that  the  absorption 
curves — i.  e.,  the  curves  of  a  against  wave-length — are  fairly  smooth,  but 
that  the  curves  of  A  against  c  are  quite  irregular.  The  inaccuracy  hi 
the  values  of  A,  as  shown  by  the  irregularities  hi  the  curves,  is  quite 
large.  In  many  cases  the  deviations  of  the  broken  line  indicate  as 
much  as  10  per  cent  variations  in  A.  The  causes  of  such  errors  are 
many.  Without  going  into  tedious  and  obvious  details,  it  is  only 
necessary  to  state  that  the  accurate  determination  of  a  depended  upon 
the  proper  choice  of  cell  depth,  which  was  regulated  by  the  actual  value 
of  the  absorption  coefficient,  as  well  as  upon  the  care  used  hi  preparing 
the  solutions  and  hi  cleaning  and  adjusting  the  cells.  Errors  also 
resulted  from  the  poor  keeping  qualities  of  certain  solutions.  The 
deflections  of  the  radiomicrometer  could  be  duplicated  to  within  a  milli- 
meter. Hence  the  ratio  of  the  deflections  for  each  cell  was  usually 
accurate  to  within  2  per  cent.  In  cases  where  the  absorption  coefficient 
was  large,  the  deflection  for  the  thick  cell  was  small  and  the  error  pro- 
portionately greater.  The  values  of  a  hi  the  tables  are  considered  to 
be  accurate  to  within  3  per  cent,  the  error  being  greater  for  very  high 
and  very  low  values  of  a.  A  was  calculated  from  formula  (2)  and  devi- 
ations of  5  to  10  per  cent  were  within  the  error  of  experiment.  The 
chance  for  error  in  A  was  much  greater  for  the  dilute  solutions  than 
for  the  more  concentrated  ones,  so  that  it  was  the  practice  to  make 
up  the  solutions  below  a  concentration  c  =  l  in  smaller  steps  than  in 
the  case  of  solutions  for  which  c  was  greater  than  1.  The  calculations 
of  a  and  A  have  been  carried  out  to  three  figures  hi  most  cases,  although 
quite  often  the  third  figure  is  not  significant. 

The  concentration  c  is  defined  to  be  the  number  of  gram-molecules 
of  salt  per  liter  of  solution,  and  the  solutions  were  prepared  hi  con- 
formity with  this.  The  calculation  for  A,  however,  has  been  made 
on  the  basis  that  c  is  the  concentration  in  gram-molecules  of  salt  per 
liter  of  solvent. 

The  procedure  of  calculating  A  by  formula  (2)  presupposes  that 
hi  1  mm.  layer  of  solution  there  is  a  1  mm.  layer  of  solvent  plus  the 
dissolved  salt.  This,  however,  is  not  strictly  true,  because  the  addition 
of  the  salt  to  the  solvent  produces  sometimes  expansion  and  some- 
times contraction.  The  error  in  the  value  of  A  due  to  this  is,  how- 
ever, negligible  in  comparison  with  the  errors  arising  hi  other  ways. 
For  example,  consider  the  case  of  an  aqueous  solution  of  CoCl2,  when 
c  =  1.90.  At  wave-length  979/^u,  a  =  0.0742.  Assuming  no  expansion 
upon  dissolving, 


18  Studies  on  Solution. 


Correcting  for  expansion  upon  dissolving,  using  data  from  Landolt 
and  Bornstein,  we  have 


In  this  case  the  correction  amounts  to  1  per  cent.  Furthermore,  the 
example  just  cited  is  one  in  which  this  correction  is  at  its  maximum. 
In  the  cases  for  solutions  which  are  more  dilute  and  for  wave-lengths 
where  the  water  absorption  is  smaller,  this  correction  is  much  less. 

In  measuring  absorption  bands  which  are  narrow  in  comparison 
with  the  range  of  wave-lengths  passing  through  the  second  slit  of  the 
spectrograph,  a  correction  for  the  finite  width  of  the  slit  must  be  made. 
All  of  the  bands  studied  in  this  investigation  were  so  broad  as  to  make 
such  a  correction  negligible. 

It  should  be  noted  that  the  spectrograph  and  radiomicrometer  of  this 
investigation  are  useful  for  a  detailed  quantitative  study  of  band 
structure.  At  no  time  in  the  present  work  has  the  full  resolving 
power  of  the  instrument  been  called  upon.  Readings  could  be  taken 
at  wave-length  intervals  of  4/iju  without  fear  of  measuring  overlapping 
regions  of  the  spectrum. 

THE  ABSORPTION  COEFFICIENT  OF  THE  SOLVENTS. 

WATER. 

The  water  used  throughout  this  investigation  was  the  same  as  that 
used  in  the  work  on  conductivity  carried  on  in  this  laboratory.  The 
water  was  dust-free  and  had  a  mean  specific  conductivity  of  1.8  X  10"6 
reciprocal  ohms.  In  view  of  the  fact  that  the  values  of  a0  for  water  are 
used  in  the  calculations  of  A  for  all  the  water  solutions,  the  absorption 
curve  of  water  was  repeated  6  times,  and  the  recorded  values  are  thus 
each  a  mean  of  12  separate  measurements. 

The  absorption  curve  for  water  in  this  region  of  the  spectrum  has 
been  drawn  by  one  other  observer,  Aschkinass.1  His  curve  is  also 
plotted  on  figure  3  for  the  sake  of  comparison.  The  lack  of  agreement 
in  the  location  of  the  position  of  the  bands  at  979/i/x  and  at  l,190juM  is 
probably  due  to  the  fact  that  Aschkinass  used  a  quartz-prism  spectro- 
graph. The  determination  of  wave-lengths  in  this  region  of  the 
spectrum  is  more  uncertain  in  the  case  of  the  prism  than  the  grating 
spectrograph.  The  values  of  a0  for  the  maximum  of  the  sharp  band 
at  979ju/z  given  by  Aschkinass  are  lower  and  those  for  the  minimum 
at  l,070ju/i  higher  than  the  corresponding  values  recorded  in  the  present 

'Wiedem.  Ann.,  55,  401  (1895). 


The  Absorption  Coefficient  of  Solution  for  Monochromatic  Radiation.      19 


work.  These  discrepancies  between  the  values  of  a0  are  such  as  arise 
from  the  use  of  an  instrument  of  low  dispersion  with  relatively  wide 
slit- widths.  Although  Aschkinass  does  not  record  the  width  of  the 
slits,  it  is  believed  that  the  employment  of  different  spectrographs  is 
the  cause  of  the  differences  in  the  values  of  OQ~. 

For  wave-lengths  shorter  than  900ju/i  the  values  of  a0  recorded  here 
are  much  greater  than  those  found  by  Aschkinass.  The  absorption 
of  water  is  quite  small  in  this  region  and  probably  Aschkinass  is  more 
nearly  correct,  for  he  was  able  to  use  longer  cells  for  the  measurements. 
However,  the  values  of  a0  found  in  this  work  are  the  ones  used  for  the 
calculations  of  A. 

TABLE  3. — The  Absorption  Coefficient  of  the  Solvents  (Fig.  3). 


Wave- 
length. 

Water. 
Temp.  =20.0° 
£  =  20  mm. 

Methyl 
alcohol. 
Temp.  =  19.2° 
4  =  20.2  mm. 

Ethyl 
alcohol. 
Temp.  =  18.9° 
*  =  20.2  mm. 

Propyl 
alcohol. 
Temp.  =  19.5° 
4  =  20.2  mm. 

Iso-butyl 
alcohol. 
Temp.  =  18.9° 
<=20.2  mm. 

Iso-amyl 
alcohol. 
Temp.  =  18.0° 
4=20.2  mm. 

605uu 

0.0002 

625 

.0002 

644 

.0004 

664 

0006 

684 

0006 

704 

0  0010 

0  0004 

0008 

724 

0015 

0004 

0010 

744 

0020 

0010 

.0012 

764 

0020 

0007 

.0012 

783 

0018 

0007 

.0010 

0.0002 

803 

0017 

0010 

.0010 

.0004 

823 

0018 

0012 

.0010 

.0004 

842 

.0026 

.0010 

0.0005 

0.0004 

.0010 

.0004 

861 

.0028 

.0010 

.0015 

.0009 

.0012 

.0004 

881 

.0032 

.0016 

.0016 

.0012 

.0018 

.0010 

901 

.0036 

.0043 

.0045 

.0034 

.0038 

.0028 

920 

.0046 

.0052 

.0038 

.0055 

.0046 

.0050 

940 

.0082 

.0027 

.0036 

.0030 

.0038 

.0028 

959 

.0191 

.0034 

.0028 

.0026 

.0028 

.0022 

978 

.0206 

.0055 

.0036 

.0026 

.0024 

.0016 

998 

.0181 

.0071 

.0051 

.0043 

.0041 

.0032 

1018 

.0139 

.0084 

.0061 

.0055 

.0056 

.0048 

1037 

.0099 

.0081 

.0058 

.0053 

.0048 

.0043 

1056 

.0075 

.0071 

.0056 

.0048 

.0046 

.0038 

1075 

.0071 

.0063 

.0050 

.0045 

.0045 

.0032 

1095 

.0084 

.0051 

.0045 

.0038 

.0034 

.0024 

1114 

.0106 

.0045 

.0038 

.0036 

.0030 

.0022 

1133 

.0161 

.0083 

.0056 

.0050 

.0045 

.0038 

1151 

.0430 

.0192 

.0138 

.0157 

.0160 

.0151 

1170 

.0525 

.0248 

.0272 

.0256 

.0269 

.0261 

1190 

.0532 

.0495 

.0495 

.0536 

.0583 

.0599 

1210 

.0530 

.0403 

.0394 

.0422 

.0420 

.0450 

1229 

.0521 

.0243 

.0306 

.0314 

.0318 

.0311 

1248 

.0489 

.0200 

.0196 

.0204 

.0175 

.0176 

1267 

.0467 

.0192 

.0154 

.0151 

.0130 

.0122 

1287 

.0494 

.0151 

.0123 

.0130 

.0094 

.0089 

1306 

.0564 

.0135 

.0111 

.0103 

.0081 

.0074 

1325 

.0680 

.0164 

.0106 

.0107 

.0075 

.0075 

1344 

.0685 

.0262 

.0149 

.0132 

.0111 

.0102 

20 


Studies  on  Solution. 


.0500 


0400 


600 


700 


800 


900 


1.000 


MOO 


1.200 


FIG.  3.— The  Absorption  Curves  for  the  Solvents. 

METHYL  ALCOHOL. 

The  methyl  alcohol  was  refluxed  and  distilled  twice  over  lime  and 
once  over  metallic  calcium.  Its  specific  gravity  at  15°  referred  to  water 
at  15°  was  0.7956.  The  figure  for  anhydrous  methyl  alcohol  given  by 
the  Bureau  of  Standards,  Bulletin  19,  page  22  (1916),  is  0.79647.  This 
indicates  that  the  methyl  alcohol  used  in  this  work  was  free  from 
water.  The  absorption  curve  for  this  alcohol  also  indicates  absence 


The  Absorption  Coefficient  of  Solution  for  Monochromatic  Radiation.      21 

of  water,  for  the  curve  shows  that  the  alcohol  becomes  transparent 
again  at  1,320/zju,  which  would  perhaps  not  be  the  case  if  water  were 
present  even  in  small  quantities,  as  pure  water  is  quite  opaque  at  this 
point.  Therefore  it  is  believed  that  the  maxima  shown  by  this  curve 
are  characteristic  of  the  alcohol  and  not  of  any  impurity. 

ETHYL  ALCOHOL. 

The  ethyl  alcohol  was  refluxed  and  distilled  repeatedly  over  lime. 
Its  density  at  25°  referred  to  water  at  4°  was  0.7851,  which  compares 
favorably  with  the  figure  0.78506  given  by  the  Bureau  of  Standards, 
Bulletin  19,  page  7  (1916). 

PROPYL  ALCOHOL. 

The  propyl  alcohol  was  refluxed  and  distilled  once  over  lime.  Its 
density  at  20°  referred  to  water  at  4°  was  0.8037.  The  figure  for  the 
anhydrous  propyl  alcohol  given  in  Van  Nostrand's  Chemical  Annual, 
1913,  page  312,  is  0.80358. 

ISO-BUTYL  ALCOHOL. 

The  iso-butyl  alcohol  was  refluxed  and  distilled  twice  over  lime.  Its 
specific  gravity  at  20°  referred  to  water  at  20°  was  0.8033.  The  figure 
given  by  Biedermann,  Chemiker  Kalender,  1915,  page  96,  is  0.8031. 
This  alcohol  showed  signs  of  slight  cloudiness  in  the  cell.  The  ab- 
sorption curve  also  shows  general  slight  absorption  in  the  visible  region 
of  wave-lengths. 

ISO-AMYL  ALCOHOL. 

The  iso-amyl  alcohol  was  refluxed  and  distilled  once  over  lime.  Its 
density  at  20°  referred  to  water  at  4°  was  0.8111.  The  figure  given  hi 
Van  Nostrand's  Chemical  Annual,  1913,  page  278,  is  0.8104. 

DISCUSSION  OF  RESULTS  WITH  THE  SOLVENTS. 

The  absorption  curves  for  water  and  the  five  alcohols  have  been 
plotted  together  for  the  sake  of  comparison  as  shown  in  figure  3.  All 
the  curves  have  a  common  axis  of  ordinates;  the  zero  of  the  ordinate 
axis  is  different  for  each  curve,  so  that  as  a  result  each  curve  is  trans- 
posed a  convenient  distance  above  the  neighboring  curve.  The 
similarity  in  the  positions  of  the  maxima  and  minima  of  the  curves 
and  the  concordance  hi  the  values  of  a0  at  these  points  are  interesting. 
Although  the  infra-red  transmission  of  the  alcohols  has  been  studied 
by  a  number  of  observers,1  no  determinations  of  the  absorption  coeffi- 
cients in  the  region  from  600^M  to  1,300/4/x  have  been  recorded.  The 
absorption  spectra  of  the  above  five  alcohols  and  many  other  sub- 
stances have  been  photographed  by  Abney  and  Testing.2  In  then- 
work  the  light  was  passed  through  a  thickness  of  3  inches  or  more  of 

,  Handbuch,  vol.  3,  p.  304.  2Phil.  Trans.  172,  887  (1881). 


22 


Studies  on  Solution. 


liquid,  and  the  spectrum  was  photographed  throughout  the  region  from 
600MM  to  l,280jzju  on  special  plates  with  a  glass-prism  spectroscope. 
Then-  spectrograms  of  the  five  alcohols  used  in  this  investigation  show 
the  existence  of  a  very  complicated  set  of  absorption  bands  and  sharp 
lines  in  this  region  of  the  spectrum.  It  was  not  possible,  however,  to 
identify  any  of  these  bands  and  lines  with  the  maxima  of  the  curves  hi 
figure  3,  for  these  absorption  curves  have  not  been  drawn  with  the 
necessary  detail. 


.0900 


.0800 


.0700 


.0200  . 


.0100  _ 


600  700  800  900  1,000  \,\00ju/i 

FIG.  4.— The  Absorption  Curves  for  Cobalt  Chloride  in  Water. 


The  Absorption  Coefficient  of  Solution  for  Monochromatic  Radiation.      23 


THE  ABSORPTION  COEFFICIENT  OF  THE  SOLUTIONS. 
COBALT  CHLORIDE  IN  WATER. 

Twenty-three  solutions  were  prepared  varying  in  concentration 
from  c  =  3.23  to  c  =  0.1.  The  more  concentrated  solutions  were  quite 
stable  and  showed  no  signs  of  decomposition,  even  after  standing  in  the 
bottles  for  several  days.  In  the  more  dilute  solutions,  however,  there 
appeared  a  flocculent  precipitate  which  increased  their  absorption  mate- 
rially. On  this  account  a  second  set  of  solutions,  whose  concentrations 
varied  from  c  =  1.0  to  c  =  0.1,  was  prepared  and  the  measurements  of 
these  appear  in  table  4. 

The  absorption  curves  include  the  long-wave  side  of  the  yellow- 
green  cobalt  absorption  band  and  the  short-wave  side  of  the  infra-red 
band,  and  show  the  region  of  transmission  between  the  two  bands. 
The  minimum  of  absorption  is  at  764ju/z. 


704^/4 


.0300  U 


.0100  _ 


.5  i.O  1.5  2.0  2.5  C        3.0 

FIG.  5.— The  A-c  Curves  for  Cobalt  Chloride  in  Water. 


24 


Studies  on  Solution. 
TABLE  4.— Cobalt  Chloride  in  Water  (Figs.  4  and  6). 


Temp.  -16.5° 

Temp.  =15.7° 

Temp.  =  15.7° 

Temp.  =  15.9° 

Temp.  =  17.8° 

Temp.  =  18.3e 

<=5  mm. 

t=5  mm. 

*=5  mm. 

*=5  mm. 

t  =  10  mm. 

(  =  10  mm. 

Wave- 

Cone. =3.227 

Cone.  =3.0 

Cone.  =2.8 

Cone.  =2.6 

Cone.  =2.4 

Cone.  =2.2 

length. 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

664/K/t 

0.0735 

0.0334 

684 

0.0795 

0.0331 

.0640 

.028: 

704 

0.107 

0.0600 

0.146 

0.0483 

0.0104 

0.0367 

0.0652 

0.0297 

.0610 

.0250 

.0480 

.0214 

724 

.0876 

.0268 

.0708 

.0231 

.0576 

.0201 

.0466 

.0174 

.0403 

.0162 

.0362 

.015? 

744 

.0571 

.0171 

.0501 

.0161 

.0444 

.0151 

.0370 

.0135 

.0328 

.0128 

.0296 

.012C 

764 

.0461 

.0138 

.0418 

.0133 

.0387 

.0131 

.0335 

.0122 

.0298 

.0116 

.0265 

.0111 

783 

.0445 

.0133 

.0413 

.0132 

.0376 

.0128 

.0324 

.0118 

.0296 

.0116 

.0265 

.0112 

803 

.0466 

.0130 

.0435 

.0140 

.0380 

.0120 

.0334 

.0122 

.0311 

.0122 

.0286 

.0122 

823 

.0406 

.0148 

.0475 

.0152 

.0401 

.0137 

.0374 

.0137 

.0340 

.0134 

.0316 

.013C 

842 

.0545 

.0161 

.0512 

.0162 

.0461 

.0155 

.0415 

.0140 

.0383 

.0149 

.0352 

.0148 

861 

.0576 

.0170 

.0558 

.0177 

.0510 

.0172 

.0450 

.0162 

.0416 

.0162 

.0376 

.0158 

881 

.0610 

.0170 

,0500 

.0186 

.0536 

.0180 

.0474 

.0170 

.0437 

.0169 

.0398 

.0167 

001 

.0647 

.0100 

.0615 

.0103 

.0568 

.0100 

.0505 

.0180 

.0460 

.0177 

.0426 

.0177 

020 

.0701 

.0200 

.0680 

.0212 

.0610 

.0201 

.0542 

.0101 

.0500 

.0175 

.0460 

.0188 

040 

.0783 

.0218 

.0760 

.0225 

.0680 

.0213 

.0626 

.0209 

.0564 

.0201 

.0526 

.0202 

060 

.0050 

.0235 

.0040 

.0250 

.0841 

.0232 

.0755 

.0217 

.0720 

.0220 

.0689 

.0226 

070 

.0834 

.0261 

.0807 

.0274 

008 

.100 

.0342 

.0921 

.0336 

Temp.  =21.3° 

Temp.  =22.0° 

Temp.  «  22.8° 

Temp.  =23.4° 

Temp.  =23.8° 

Temp.  =22.3° 

t  =  10  mm. 

t  =  10  mm. 

t  =  10  mm. 

<  =  10mm. 

t  =  10  mm. 

<  =  10  mm. 

Wave- 

Cone. =  1.08 

Cone.  =  1.0 

Cone.  =  1.7 

Cone.  =  1.6 

Cone.  =  1.5 

Conc.  =  l. 

length. 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

605/zM 

0.0048 

0.0478 

0.0865 

0.0455 

0.0755 

0.0444 

0.0695 

0.0434 

0.0652 

0.0435 

0.0589 

0.0420 

625 

.0834 

.0418 

.0783 

.0413 

.0670 

.030* 

.0614 

.0384 

.0574 

.0383 

.0502 

.0359 

644 

.0726 

.0366 

.0602 

.0364 

.0587 

.0345 

.0540 

.0338 

.0506 

.0337 

.0446 

.0319 

664 

.0620 

.0317 

.0500 

.0315 

.0  08 

.0203 

.0471 

.0294 

.0434 

.0289 

.0378 

.0270 

684 

.0500 

.0255 

.0458 

.0241 

.0407 

.0230 

.0387 

.0241 

.0357 

.0237 

.0315 

.0225 

704 

.0370 

.0182 

.0340 

.0170 

.0315 

.0170 

.0290 

.0175 

.0267 

.0171 

.0229 

.0156 

724 

.0276 

.0132 

.0260 

.0120 

.0220 

.0126 

.0208 

.0121 

.0198 

.0122 

.0172 

.0112 

744 

.0233 

.0108 

.0213 

.0101 

.0101 

.0100 

.0173 

.0096 

.0164 

.0096 

.0144 

.0087 

764 

.0215 

.0008 

.0107 

.0003 

.0173 

.0090 

.0164 

.0090 

.0153 

.0089 

.0136 

.0083 

783 

.0235 

.0110 

.0201 

.0006 

.0181 

.0096 

.0168 

.0094 

.0159 

.0094 

.0143 

.0089 

803 

.0246 

.0116 

.0225 

.0100 

.0200 

.0108 

.0187 

.0106 

.0178 

.0107 

.0161 

.0103 

823 

.0275 

.0130 

.0250 

.0127 

.0228 

.0124 

.0215 

.0125 

.0202 

.0123 

.0188 

.0121 

842 

.0300 

.0143 

.0202 

.0140 

.0260 

.0138 

.0247 

.0138 

.0232 

.0137 

.0217 

.0136 

861 

.0336 

.0156 

.0318 

.0153 

.0285 

.0151 

.0271 

.0152 

.0256 

.0152 

.0234 

.0147 

881 

.0358 

.0165 

.0330 

.0162 

.0307 

.0162 

.0290 

.0162 

.0270 

.0159 

,0250 

.0156 

001 

.0384 

.0175 

.0362 

.0171 

.0327 

.0171 

.0310 

.0171 

.0290 

.0170 

.0269 

.0167 

020 

.0414 

.0186 

.0302 

.0182 

.0353 

.0181 

.0336 

.0181 

.0320 

.0182 

.0301 

.0182 

040 

.0472 

.0107 

.0456 

.0107 

.0414 

.0195 

.0398 

.0198 

.0381 

.0199 

.0358 

.0198 

060 

.0638 

.0224 

.0615 

.0223 

.0558 

.0222 

.0541 

.0218 

.0522 

.0221 

.0492 

.0215 

070 

.0754 

.0276 

.0742 

.0282 

.0661 

.0268 

.0637 

.0270 

.0618 

.0274 

.0596 

.0278 

008 

.0858 

.0342 

.0826 

.0338 

.0751 

.0335 

.0716 

.0335 

.0688 

.0338 

.0653 

.0336 

1018 

.0848 

.0415 

.0798 

.0408 

.0776 

.0425 

.0725 

.0418 

1037 

.0916 

.0510 

.0870 

.0513 

.0820 

.0516 

The  Absorption  Coefficient  of  Solution  for  Monochromatic  Radiation.      25 


TABLE  4.— Cobalt  Chloride  in  Water— Continued. 


Temp.  =  18.9° 

Temp.  =20.7° 

Temp.  =20.5° 

Temp.  =20.3° 

Temp.  =20.2° 

Temp.  =  19.8° 

*  =  10  mm. 

<  =  10  mm. 

<  =  10  mm. 

«=20mm. 

*  =  20mm. 

<=20mm. 

Wave- 

Cone. =  1.3 

Cone.  =  1.2 

Cone.  =  1.1 

Cone.  =  1.0 

Cone.  =0.8 

Cone.  =0.6 

length. 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

605MM 

0.0528 

0.0406 

0.0500 

0.0417 

3.0447 

0.0406 

0.0384 

0.0384 

0.0317 

0.0396 

0.0235 

0.0392 

625 

.0463 

.0356 

.0427 

.0355 

.0384 

.0349 

.0334 

.0338 

.0290 

.0362 

.0222 

.0370 

644 

.0398 

.0306 

.0371 

.0308 

.0340 

.0309 

.0292 

.0292 

.0239 

.0299 

.0204 

.0340 

664 

.0338 

.0260 

.0317 

.0264 

.0293 

.0267 

.0246 

.0246 

.0214 

.0269 

.0175 

.0292 

684 

.0272 

.0209 

.0254 

.0212 

.0228 

.0207 

.0195 

.0195 

.0163 

.0204 

.0139 

.0232 

704 

.0200 

.0146 

.0187 

.0145 

.0165 

.0141 

.0147 

.0137 

.0127 

.0148 

.0109 

.0165 

724 

.0152 

.0105 

.0140 

.0104 

.0126 

.0101 

.0114 

.0099 

.0110 

.0120 

.0087 

.0120 

744 

.0130 

.0085 

.0123 

.0088 

.0107 

.0079 

.0097 

.0077 

.0085 

.0081 

.0081 

.0102 

764 

.0123 

.0078 

.0110 

.0075 

.0104 

.0076 

.0095 

.0075 

.0081 

.0076 

.0068 

.0080 

783 

.0131 

.0087 

.0122 

.0088 

.0109 

.0083 

.0100 

.0082 

.0082 

.0080 

.0065 

.0078 

803 

.0147 

.0100 

.0139 

.0102 

.0125 

.0098 

.0114 

.0097 

.0095 

.0098 

.0082 

.0108 

823 

.0173 

.0119 

.0162 

.0120 

.0143 

.0113 

.0133 

.0115 

.0106 

.0110 

.0087 

.0115 

842 

.0202 

.0135 

.0185 

.0133 

.0169 

.0130 

.0159 

.0133 

.0131 

.0131 

.0111 

.0142 

861 

.0220 

.0148 

.0205 

.0146 

.0189 

.0145 

.0178 

.0150 

.0149 

.0151 

.0124 

.0160 

881 

.0234 

.0155 

.0221 

.0157 

.0205 

.0157 

.0187 

.0155 

.0155 

.0154 

.0132 

.0167 

901 

.0252 

.0174 

.0237 

.0168 

.0218 

.0165 

.0200 

.0164 

.0172 

.0170 

.0140 

.0173 

920 

.0281 

.0181 

.0265 

.0182 

.0241 

.0177 

.0221 

.0175 

.0181 

.0174 

.0154 

.0180 

940 

.0335 

.0195 

.0319 

.0194 

.0302 

.0200 

.0276 

.0194 

.0239 

.0196 

.0197 

.0192 

960 

.0472 

.0216 

.0453 

.0218 

.0422 

.0219 

.0402 

.0211 

.0363 

.0215 

.0314 

.0205 

979 

.0555 

.0268 

.0541 

.0269 

.0512 

.0278 

.0476 

.0270 

.0417 

.0276 

.0371 

.0275 

998 

.0615 

.0334 

.0598 

.0348 

.0546 

.0333 

.0518 

.0337 

.0455 

.0342 

.0387 

.0343 

1018 

.0676 

.0413 

.0648 

.0424 

.0596 

.0414 

.0560 

.0421 

.0480 

.042^ 

.0400 

.0417 

1037 

.0767 

.0511 

.0726 

.0522 

.0658 

.0509 

.0610 

.0511 

.0525 

.0536 

.0423 

.0540 

1056 

.0466 

.0652 

1076 

.0528 

.0762 

1095 

.0607 

.0872 

Temp.  =20.0° 

Temp.  =20.0° 

Temp.  =20.4° 

Temp.  =20.0° 

Temp.  =20.4° 

*  =  20  mm. 

<  =  20mm. 

t  —  20  mm. 

t  =  20  mm. 

J  =  20  mm. 

Wave- 

Cone. =0.5 

Cone.  =0.4 

Cone.  =0.3 

Cone.  =0.2 

Cone.  =0.1 

length. 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

605/z/z 

0.0210 

0.0420 

0.0163 

0.0408 

0.0124 

0.0413 

0.0082 

0.0410 

0.0043 

0.0430 

625 

.0186 

.0371 

.0144 

.0360 

.0115 

.0383 

.0071 

.0355 

.0042 

.0420 

644 

.0173 

.0346 

.0137 

.0342 

.0102 

.0340 

.0065 

.0325 

.0040 

.0400 

664 

.0149 

.0298 

.0116 

.0290 

.0088 

.0293 

.0055 

.0275 

.0033 

.0330 

684 

.0123 

.0246 

.0095 

.0242 

.0068 

.0227 

.0047 

.0235 

.0028 

.0280 

704 

.0088 

.0156 

.0076 

.0165 

.0056 

.0153 

.0039 

.0145 

.0025 

.0150 

724 

.0076 

.0122 

.0062 

.0117 

.0047 

.0107 

.0035 

.0100 

.0025 

.0100 

744 

.0072 

.0104 

.0058 

.0095 

.0045 

.0083 

.0035 

.0075 

.0024 

.0090 

764 

.0058 

.0076 

.0055 

.0087 

.0043 

.0077 

.0034 

.0070 

.0027 

.0070 

783 

.0063 

.0090 

.0052 

.0085 

.0043 

.0083 

.0034 

.0080 

.0027 

.0090 

803 

.0074 

.0113 

.0065 

.0120 

.0050 

.0110 

.0036 

.0095 

.0027 

.0100 

823 

.0075 

.0114 

.0070 

.0130 

.0065 

.0156 

.0034 

.0080 

.0032 

.0140 

842 

.0097 

.0142 

.0080 

.0135 

.0068 

.0140 

.0045 

.0135 

.0038 

.0120 

861 

.0104 

.0152 

.0091 

.0157 

.0073 

.0150 

.0049 

.0105 

.0041 

.0120 

881 

.0113 

.0162 

.0103 

.0177 

.0078 

.0153 

.0064 

.0160 

.0043 

.0110 

901 

.0121 

.0190 

.0114 

.0195 

.0088 

.0173 

.0070 

.0170 

.0050 

.0140 

920 

.0134 

.0176 

.0126 

.0200 

.0102 

.0186 

.0081 

.0175 

.0064 

.0180 

940 

.0180 

.0196 

.0160 

.0195 

.0144 

.0207 

.0124 

.0210 

.0106 

.0240 

960 

.0303 

.0224 

.0278 

.0219 

.0261 

.0233 

.0233 

.0210 

.0212 

.0210 

979 

.03  6 

.0280 

.0318 

.0280 

.0290 

.0313 

.0269 

.0315 

.0237 

.0310 

998 

.0354 

.0346 

.0326 

.0362 

.0284 

.0343 

.0250 

.0345 

.0216 

.0350 

1018 

.0354 

.0430 

.0321 

.0455 

.0279 

.0467 

.0232 

.0465 

.0183 

.0440 

1037 

.0366 

.0534 

.0320 

.0552 

.0255 

.0523 

.0207 

.0540 

.0153 

.0540 

1056 

.0401 

.0652 

.0348 

.0682 

.0267 

.0640 

.0204 

.0645 

.0147 

.0720 

1076 

.0459 

.0776 

.0402 

.0827 

.0297 

.0753 

.0228 

.0785 

.0144 

.0730 

1095 

.0548 

.0928 

.0460 

.0890 

.0359 

.0917 

.0266 

.0910 

.0178 

.0940 

1115 

.0626 

.104 

.0550 

.111 

.0427 

.140 

.0313 

.104 

.0212 

.106 

1134 

.0742 

.116 

.0615 

.109 

.0483 

.107 

.0405 

.122 

.0280 

.119 

26 


Studies  on  Solution. 


The  A—  c  curves  for  wave-lengths  605/i/i  to  764/z/z,  inclusive,  lying 
on  the  edge  of  the  yellow-green  band,  show  that  A  decreases  in  a 
marked  manner  with  dilution  and  reaches  a  minimum  value  at  about 
c  =  1 .0.  Below  c  =  1 .0,  A  shows  a  slight  increase. 

The  A  —  c  curves  for  those  wave-lengths  in  the  region  of  transparency, 
from  842/x/x  to  979jujLi,  are  straight  lines  parallel  to  the  abscissae,  show- 
ing that  A  in  this  region  is  constant  for  all  concentrations.  For  wave- 
lengths greater  than  979/z/x,  which  lie  on  the  edge  of  the  infra-red  band, 
A  is  a  constant  within  the  error  of  experiment.  The  two  band-edges  in 
question  are  thus  seen  to  behave  quite  differently  as  dilution  proceeds. 

Houstoun1  has  drawn  the  absorption  curves  for  two  solutions  of  cobalt 
chloride  in  water,  and  table  5  shows  the  comparison  between  his  values 
and  the  values  interpolated  from  table  4. 

TABLE  5.— 4  for  Cobalt  Chloride  in  Water. 


Wave-length. 

c=0.65 

c=3.10 

Houstoun. 

From  table  4. 

Houstoun. 

From  table  4. 

645MM 
684 
720 
750 
794 
850 
910 
980 
1070 

0.041 
.024 
.031 
.028 
.028 
.028 
.028 
.040 
.070 

0.0340 
.0232 
.0123 
.0090 
.0109 
.0147 
.0175 
.0275 
.0762 

6.200 
.041 
.037 
.016 
.018 
.029 
.038 
.074 

0.0330 
.0150 
.0138 
.0165 
.0198 

The  agreement  between  Houstoun's  values  and  the  values  of  A  found 
in  the  present  investigation  is  far  from  satisfactory.  However,  both 
sets  indicate  similar  changes  in  A  with  c. 

COBALT  CHLORIDE  IN  METHYL  ALCOHOL. 

Seven  solutions  were  prepared  varying  in  concentration  from 
c  =  0.7  to  c  =  0.1.  The  solutions  appeared  to  keep  very  well,  and  no 
such  precipitate  was  formed  as  was  noticed  hi  the  aqueous  solutions. 
The  absorption  curves  show  that  the  character  of  the  absorption  of 
the  alcohol  solutions  was  quite  different  from  that  of  the  aqueous 
solutions,  the  absorption  curve  for  the  alcohol  solution  being  shifted 
towards  the  red,  so  that  the  minimum  of  absorption  was  now  at  842/i/i, 
the  shift  thus  amounting  to  about  SOjuM-  The  shift  towards  the  red  of 
the  edge  of  the  band  in  the  green  was  sufficient  to  make  this  band 
absorb  nearly  all  of  the  visible  red  light.  (Instead  of  speaking  of  the 
"shift  of  a  band/'  some  have  preferred  to  speak  of  the  bands  in  the 

1Proc.  Roy.  Soc.  Edinburgh,  31,  521  (1910-11). 


The  Absorption  Coefficient  of  Solution  for  Monochromatic  Radiation.      27 

different  solvents  as  entirely  different  bands.)  As  a  consequence,  the 
more  concentrated  solutions  appeared  a  deep  purple,  becoming  more 
and  more  pink  as  the  dilution  increased. 

The  A  -c  curve  for  744/iM  shows  that  A  decreases  by  a  large  amount 
with  dilution,  dropping  from  0.128  for  c  =  0.7  to  0.080  for  c  =  0.1. 
This  is  the  only  A  -c  curve  which  has  been  plotted  for  a  wave-length 


.1         .£          .3          4          .5          .6    C    .7 


•700  800  900  1,000  '1,100          .         1,20  !.$00/</l 

FIG.  6.— The  A-c  and  Absorption  Curves  for  Cobalt  Chloride  in  Methyl  Alcohol. 


Studies  on  Solution. 


TABLE  6.— Cobalt  Chloride  in  Methyl  Alcohol  (Fig.  6). 


Temp.  =21.5° 

Temp.  =21.0° 

Temp.  =20.9° 

Temp.  =20.7° 

Temp.  =21.0° 

Temp.  =19.8° 

Temp.  =19.0° 

t=  10.5  mm. 

<  =  10.5  mm. 

t-  10.5  mm. 

<=  10.5  mm. 

<=10.5  mm. 

<=20.2  mm. 

t  =20.2  mm. 

Wave- 

Cone. =0.7 

Cone.  =0.6 

Cone.  =0.5 

Cone.  =0.4 

Cone.  =0.3 

Cone.  =0.2 

Cone.  =0.1 

length. 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

704/u/t 

0.0274 

0.270 

724 

0.125 

0.310 

0.0722 

0.239 

0.0326 

0.161 

.0084 

.080 

744 

0.0806 

0.128 

0.0646 

0.106 

0.0434 

0.0848 

.0275 

.0663 

.0174 

.0547 

.0106 

.0480 

.0048 

.038 

764 

.0214 

.0294 

.0167 

.0266 

.0128 

.0242 

.0108 

.0253 

.0082 

.0250 

.0062 

.0275 

.0038 

.031 

803 

.0128 

.0169 

.0102 

.0154 

.0075 

.0130 

.0069 

.0148 

.0054 

.0143 

.0043 

.0165 

.0030 

.020 

842 

.0118 

.0154 

.0082 

.0120 

.0065 

.0110 

.0051 

.0103 

.0047 

.0123 

.0035 

.0125 

.0025 

.015 

881 

.0148 

.0189 

.0121 

.0176 

.0095 

.0158 

.0082 

.0165 

.0067 

.0153 

.0059 

.0215 

.0041 

.025 

920 

.0191 

.0199 

.0172 

.0200 

.0147 

.0190 

.0133 

.0203 

.0115 

.0210 

.0102 

.0250 

.0077 

.025 

959 

.0237 

.0290 

.0197 

.0276 

.0159 

.0250 

.0139 

.0263 

.0106 

.0240 

.0087 

.0265 

.0066 

.032 

978 

.0278 

.0319 

.0242 

.0312 

.0196 

.0282 

.0173 

.0295 

.0142 

.0323 

.0118 

.0315 

.0087 

.032 

1018 

.0408 

.0463 

.0349 

.0441 

.0296 

.0424 

.0263 

.0448 

.0213 

.0430 

.0165 

.0405 

.0134 

.050 

1056 

.0528 

.0653 

.0440 

.0649 

.0380 

.0618 

.0332 

.0628 

.0257 

.0620 

.0204 

.0665 

.0142 

.071 

1095 

.0700 

.0927 

.0604 

.0921 

.0488 

.0874 

.0425 

.0935 

.0321 

.0900 

.0232 

.0905 

.0149 

.098 

1133 

.109 

.144 

.0929 

.141 

.0726 

.129 

.0628 

.136 

.0473 

.130 

.0358 

.138 

.0223 

.140 

TABLE  7.— Cobalt  Chloride  in  Ethyl  Alcohol  (Fig.  7). 


Temp.  =20.0° 

Temp.  =20.2° 

Temp.  =20.4° 

Temp.  =20.3° 

Temp.  =20.6° 

Temp.  =21.2° 

t  =6.36  mm. 

t  =6.36  mm. 

f  =10.5  mm. 

<=10.5  mm. 

t  =2.73  mm. 

t  =2.73  mm. 

Wave- 

Cone. =0.40 

Cone.  =0.30 

Cone.  =0.20 

Cone.  =0.10 

Cone.  =0.08 

Cone.  =0.06 

length. 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

724/10 

0.0504 

0.63 

0.0366 

0.61 

744 

0.0953 

0.238 

0.0787 

0.196 

0.0357 

0.179 

0.0136 

0.136 

.0105 

.13 

764 

0249 

062 

0184 

061 

0124 

062 

0047 

047 

803 

0175 

044 

0131 

044 

0093 

047 

0035 

035 

842 

.0175 

042 

0124 

040 

0088 

042 

.0039 

.034 

881 

.0191 

.044 

0147 

037 

.0102 

.043 

.0047 

.031 

920 

.0244 

.051 

.0205 

.056 

.0148 

.055 

.0086 

.048 

959 

0272 

061 

0225 

066 

0165 

069 

0089 

061 

978 

0316 

070 

0253 

072 

0190 

077 

0115 

079 

1018 

.0459 

099 

0382 

107 

0293 

116 

.0190 

.129 

1056 

.0666 

.152 

.0570 

.171 

.0418 

.181 

.0266 

.210 

.0237 

.22 

.0208 

.25 

1095 

.106 

.252 

.0857 

.271 

.0648 

.301 

.0400 

.355 

.0314 

.34 

.0289 

.38 

1133 

.170 

.410 

.143 

.457 

.0943 

.493 

.0645 

.589 

.0543 

.61 

.0475 

.68 

Temp.  =20.7° 

Temp.  =21.5° 

Temp.  =21.7° 

Temp.  =21.2° 

Temp.  =21.3° 

Temp.  =21.3° 

t  =7.39  mm. 

t  =11.55  mm. 

«=  11.55  mm. 

t  —  11.55  mm. 

<  =  11.55  mm. 

*=  11.55  mm. 

Wave- 

Cone. =0.05 

Cone.  =0.04 

Cone.  =0.03 

Cone.  =0.02 

Cone.  =0.01 

Cone.  =0.005 

length. 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

704/ui 

0  0922 

3.1 

0.0527 

2.6 

0.0225 

2.3 

0.0094 

1.9 

724 

0.0291 

0.58 

0.0203 

0.51 

.0172 

0.57 

.0081 

0.40 

.0042 

0.42 

.0022 

0.44 

1056 

.0174 

.22 

.0164 

.27 

.0110 

.18 

.0106 

.26 

.0078 

.22 

.0069 

.26 

1095 

.0214 

.34 

.0204 

.39 

.0148 

.34 

.0138 

.46 

.0081 

.36 

.0065 

.40 

1133 

.0357 

.60 

.0316 

.65 

.0246 

.63 

.0192 

.67 

.0142 

.86 

.0103 

.94 

The  Absorption  Coefficient  of  Solution  for  Monochromatic  Radiation.     29 

lying  on  the  edge  of  the  red-yellow  absorption  band,  for  this  edge  is 
extremely  sharp  compared  to  the  edge  of  the  analogous  band  of  the 
water  solution.  The  A  —  c  curves  for  the  region  of  transmission  764ju/* 
to  920juju,  and  for  the  edge  of  the  infra-red  band  920/iju  to  1,134/i/i, 
show  that  A  for  these  regions  of  the  spectrum  remains  approximately 
constant  for  all  concentrations. 

COBALT  CHLORIDE  IN  ETHYL  ALCOHOL. 

Four  solutions  were  prepared  varying  in  concentration  from  c=0.4 
to  c=0.1.  A  month  later  a  second  series  of  more  dilute  solutions,  for 
which  c  was  0.08,  0.06,  0.05,  0.04,  0.03,  0.02,  0.01,  0.005,  were  prepared; 
their  absorption  curves  were  drawn  only  in  the  region  of  moderate 
absorption,  from  1,056/i/x  to  l,134juju  and  for  724/jju  and  704juju;  in  the 
other  regions  they  either  absorbed  too  much  or  too  little,  so  that  no 
confidence  could  be  placed  in  the  values  of  A. 


.40 


1.000  1,100  1.ZQO  1,300/4* 

FIG.  7.— The  A-c  and  Absorption  Curves  for  Cobalt  Chloride  in  Ethyl  Alcohol. 


Studies  on  Solution. 


The  absorption  curves  for  the  solutions  of  ethyl  alcohol  are  similar 
in  their  general  character  to  those  for  methyl  alcohol.  The  minimum 
of  absorption  occurs  in  the  same  place,  at  842/z/z,  and  the  steepness  of 
the  edges  of  the  bands  is  much  the  same.  The  ethyl-alcohol  solutions 
were  of  a  pure  deep-blue  in  the  higher  concentrations,  becoming  a 
greenish  blue  as  dilution  increased. 

The  A  —  c  curves  for  724/*M  and  744/i/x  show  that  A  decreases  with 
dilution,  and  the  decrease  in  this  case  is  far  greater  than  in  the  case  of 
methyl  alcohol.  For  wave-lengths  764juju  to  979/^u  in  the  region  of 
transmission,  A  is  fairly  constant.  For  the  region  on  the  edge  of  the 
infra-red  band,  1,018/iM  to  l,134/*/i,  the  A—c  curves  show  that  A 
increases  with  dilution.  These  last-mentioned  curves  illustrate  the 
magnitude  of  the  error  in  the  determination  of  A  in  the  case  of  very 
dilute  solutions. 

TABLE  8.— Cobalt  Chloride  in  Propyl  Alcohol  (Fig.  8). 


Temp.  =22.0° 

Temp.  =21.5° 

Temp.  =21.9° 

Temp.  =22.1° 

*=10.5  mm. 

«=10.5  mm. 

t  =  10.5  mm. 

*=10.5  mm. 

Wave- 

Cone. =0.434 

Cone.  =0.40 

Cone.  =0.35 

Cone.  =0,30 

length. 

a 

A 

a 

A 

a 

A 

a 

A 

744W. 

0.107 

0.246 

0.0992 

0.223 

0.0797 

0.227 

0.0642 

0.214 

764 

.0250 

.0575 

.0205 

.0549 

.0197 

.0578 

.0189 

.0630 

803 

.0159 

.0365 

.0142 

.0355 

.0142 

.0405 

.0133 

.0443 

842 

.0153 

.0344 

.0139 

.0338 

.0136 

.0377 

.0121 

.0390 

881 

.0176 

.0378 

.0156 

.0360 

.0162 

.0428 

.0142 

.0433 

920 

.0252 

.0454 

.0232 

.0443 

.0227 

.0491 

.0213 

.0527 

959 

.0277 

.0578 

.0254 

.0570 

.0241 

.0613 

.0227 

.0663 

978 

.0320 

.0675 

.0295 

.0673 

.0278 

.0719 

.0254 

.0760 

1018 

.0460 

.0908 

.0439 

.0960 

.0418 

.104 

.0384 

.109 

1056 

.0704 

.151 

.0662 

.153 

.0631 

.169 

.0568 

.173 

1095 

.114 

.253 

.107 

.258 

.0976 

.267 

.0917 

.292 

Temp.  =22.3° 

Temp.  =20.0° 

Temp.  =19.5° 

Temp.  =19.7° 

<=10.5  mm. 

t  =  10.5  mm. 

<=  10.5  mm. 

*=20.2  mm. 

Wave- 

Cone. =0.25 

Cone.  =0.20 

Cone.  =0.15 

Cone.  =0.10 

length. 

a 

A 

a 

A 

a 

A 

a 

A 

744/iM 

0.0512 

0.205 

0.0357 

0.178 

0.0236 

0.158 

0.0160 

0.160 

764 

.0148 

.0592 

.0115 

.0575 

.0082 

.0547 

.0064 

.0640 

803 

.0111 

.0445 

.0089 

.0445 

.0065 

.0434 

.0052 

.0520 

842 

.0106 

.0408 

.0086 

.0410 

.0065 

.0407 

.0061 

.0570 

881 

.0118 

.0424 

.0102 

.0450 

.0079 

.0447 

.0073 

.0610 

920 

.0183 

.0512 

.0159 

.0520 

.0142 

.0580 

.0122 

.0670 

959 

.0194 

.0672 

.0165 

.0695 

.0128 

.0680 

.0106 

.0800 

978 

.0228 

.0808 

.0190 

.0820 

.0150 

.0822 

.0123 

.0970 

1018 

.0311 

.112 

.0297 

.121 

.0246 

.127 

.0197 

.142 

1056 

.0505 

.183 

.0440 

.196 

.0355 

.211 

.0275 

.227 

1095 

.0816 

.301 

.0654 

.308 

.0549 

.342 

.0418 

.380 

.;  .,„,.  -,  . 

The  Absorption  Coefficient  of  Solution  for  Monochromatic  Radiation.      31 

COBALT  CHLORIDE  IN  PROPYL  ALCOHOL. 

Eight  solutions  were  prepared  varying  in  concentration  from  c  =  0.434 
to  c  =  0.10.  'The  character  of  the  absorption  curves  is  the  same  as  that 
of  the  ethyl-alcohol  solutions,  the  minimum  of  absorption  occurring 
again  at  842/iju  and  the  steepness  of  the  edges  of  the  bands  being 
similar.  The  propyl-alcohol  solutions  were  also  deep  blue,  becoming 
a  greenish  blue  upon  dilution.  The  absorption  curve  for  c  =  0.434  has 
been  drawn  in  greater  detail,  readings  having  been  taken  at  every  10/x/i. 

The  A—c  curve  for  744/iju,  lying  on  the  edge  of  the  yellow-red 
absorption  band,  shows  that  A  decreases  greatly  with  dilution.  This 


800  900  1,000  1,100  I, ZOO  1,300  A/* 

FIG.  8.— The  A-c  and  Absorption  Curves  for  Cobalt  Chloride  in  Propyl  Alcohol. 


32 


Studies  on  Solution. 


curve  (and  the  A  — c  curves  for  1,056/zju  and  1,095/i/z)  have  been  plotted 
on  a  scale  of  ordinates  one-tenth  as  great  as  the  other  A—  c  curves. 
For  wave-lengths  hi  the  region  of  low  absorption,  764juM  to  842/z/z,  A  is 
approximately  constant,  although  hi  this  region  the  values  of  a  are  so 
small  that  the  values  of  A  are  liable  to  considerable  inaccuracy.  The 
A— c  curves  for  wave-lengths  920/^Lt  to  1,095/z/z,  on  the  edge  of  the 
infra-red  band,  show  that  A  increases  rapidly  with  dilution. 

COBALT  CHLORIDE  IN  ISO-BUTYL  ALCOHOL. 

Four  solutions  were  prepared  varying  in  concentration  from  c  =  0.194 
to  c  =  0.05.  The  absorption  curves  have  the  same  character  as  those 
for  the  ethyl-alcohol  solutions  and  the  color  of  the  solutions  in  the 
bottles  was  the  same,  being  a  deep  blue  which  changed  to  a  greenish 

TABLE  9.— Cobalt  Chloride  in  Iso-butyl  Alcohol  (Fig.  9). 


Temp.  =20.2° 

Temp.  =20.8° 

Temp.  =21.0° 

Temp.  =21.2° 

£=10.5  mm. 

£=10.5  mm. 

<=10.5  mm. 

t  =20.2  mm. 

Wave- 

Cone. =0.194 

Cone.  =0.15 

Cone.  =0.10 

Cone.  =0.05 

length. 

a 

A 

a 

A 

a 

A 

a 

A 

734/iM 

0.0873 

0.443 

0.0634 

0.416 

0.0370 

0.359 

0.0155 

0.288 

744 

.0316 

.157 

.0247 

.157 

.0148 

.136 

.0884 

.144 

754 

.0128 

.0598 

.0115 

.0686 

.0075 

.0630 

.0056 

.0880 

764 

.0075 

.0325 

.0075 

.0420 

.0051 

.0390 

.0048 

.0720 

803 

.0054 

.0227 

.0054 

.0293 

.0035 

.0250 

.0041 

.0620 

842 

.0051 

.0211 

.0051 

.0273 

.0035 

.0250 

.0041 

.0620 

881 

.0065 

.0242 

.0065 

.0313 

.0043 

.0250 

.0046 

.0560 

920 

.0109 

.0325 

.0102 

.0373 

.0036 

.0400 

.0081 

.0700 

959 

.0118 

.0464 

.0102 

.0493 

.0086 

.0580 

.0069 

.0820 

978 

.0133 

.0561 

.0115 

.0607 

.0089 

.0650 

.0071 

.0940 

1018 

.0231 

.0903 

.0197 

.0940 

.0150 

.0940 

.0119 

.126 

1056 

.0351 

.157 

.0281 

.157 

.0217 

.171 

.0142 

.192 

1095 

.0568 

.275 

.0441 

.271 

.0319 

.275 

.0191 

.314 

1133 

.0954 

.468 

.0738 

.461 

.0538 

.493 

.0302 

.514 

blue  upon  dilution.  In  preparing  the  solutions  the  usual  procedure 
was  followed,  namely,  to  make  the  dilutions  by  adding  pure  alcohol 
to  the  saturated  mother  solution.  It  was  found  that  a  precipitate 
appeared  immediately  upon  dilution.  The  solutions  were  then 
filtered  and  the  concentrations  were  measured  by  a  determination  of 
the  density.  The  value  of  the  concentration  determined  in  this  way 
was  found  to  agree  within  the  error  of  experiment  with  the  concentra- 
tion calculated  from  the  known  amount  of  dilution.  This  showed  that 
the  loss  by  precipitation  was  either  negligible  or  that  the  precipitate 
contained  nearly  equal  parts  of  cobalt  chloride  and  iso-butyl  alcohol. 
The  filtered  solutions  appeared  quite  free  from  any  visible  particles. 
In  the  cells  they  had  a  somewhat  cloudy  appearance,  suggestive  of 


The  Absorption  Coefficient  of  Solution  for  Monochromatic  Radiation.      33 

a  colloid  condition.  They  showed  slightly  a  Tyndall  cone  in  blue 
light.  An  examination  of  these  freshly  filtered  iso-butyl  alcohol  (and 
also  the  iso-amyl  alcohol)  solutions  with  the  ultra-microscope  showed 
that  they  were  not  colloidal  in  nature,  but  that  they  contained  a 
number  of  particles.  Whether  these  particles  were  newly  formed 
precipitate  or  some  impurity  is  unknown. 


.194 


CoCI2.m  Iso-butyl  alcohol 


800  900  1,000  1,100  1,200  1,300/4/4 

FIG.  9.— The  A-c  and  Absorption  Curves  for  Cobalt  Chloride  in  Iso-Butyl  Alcohol. 

The  A—c  curves  for  734/zju  and  744juju  wave-lengths  lying  on  the 
edge  of  the  yellow-red  absorption  band  show  again  that  A  decreases 
rapidly  with  dilution.  For  the  wave-lengths  754^  and  764ju/i  in  the 
region  of  transmission  A  is  constant.  The  behavior  of  the  edge  of  the 
infra-red  band  is  similar  to  the  case  of  the  propyl-alcohol  solutions,  for 
A  increases  with  dilution,  as  shown  by  the  rise  in  the  A  —  c  curves  for 
wave-lengths  l,018juju  to  l,133w- 

COBALT  CHLORIDE  IN  ISO-AMYL  ALCOHOL. 

Six  solutions  were  prepared  varying  in  concentration  from  c  =  0.064 
to  c  =  0.010.  The  solutions  in  the  bottles  were  of  a  deep  blue  in  the 
higher  concentrations,  which  changed  to  a  greenish  blue  upon  dilution. 


34 


Studies  on  Solution. 


The  general  character  of  the  absorption  curves  is  the  same  as  that  of  the 
ethyl-alcohol  solutions. 

The  iso-amyl  alcohol  solutions  exhibited  the  same  phenomenon  of 
precipitation  upon  dilution  as  has  been  described  in  the  case  of  the  iso- 
butyl  alcohol  solutions.  They  also  had  the  same  appearance  in  the 
cells  and  under  the  ultra-microscope. 

TABLE  10.— Cofcofc  Chloride  in  lao-Amyl  Alcohol  (Fig.  10). 


Temp.  =22.1° 

Temp.  -23.4° 

Temp.  -21.4° 

Temp.  -21.4° 

Temp.  -21.9° 

Temp.  -23.8° 

/=10.5  mm. 

<=10.5  mm. 

£=10.5  mm. 

/=10.5  mm. 

t  -20.2  mm. 

t  —20.2  mm. 

Wave- 

Cone. =0.064 

Cone.  =0.05 

Cone.  -0.04 

Cone.  ^0.03 

Cone.  -0.02 

Cone.  -0.01 

length. 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

704/a/i 

0.0278 

2.78 

714 

0.0680 

1.70 

0.0455 

1.52 

0.0267 

1.34 

.0112 

1  12 

724 

0.0569 

0.89 

0.0395 

0.79 

.0269 

o!e7 

.0181 

0.60 

!oi!3 

0*56 

4061 

X  •  ikA 

0.51 

734 

.0242 

.38 

.0156 

.31 

.0108 

.27 

.0079 

.26 

.0060 

.30 

.0039 

.39 

744 

.0095 

.15 

.0075 

.15 

.0050 

.13 

.0069 

.23 

.0045 

.22 

.0032 

.32 

764 

.0031 

.05 

.0031 

.06 

.0028 

.07 

.0028 

.08 

.0030 

.15 

.0024 

.24 

803 

.0028 

.05 

.0028 

.05 

.0028 

.07 

.0024 

.07 

.0022 

.09 

.0024 

.20 

842 

.0031 

.05 

.0031 

.05 

.0031 

.08 

.0028 

.08 

.0023 

.10 

.0034 

.30 

881 

.0054 

.08 

.0059 

.10 

.0050 

.10 

.0050 

.13 

.0046 

.18 

.  0056 

.46 

920 

.0118 

.11 

.0118 

.14 

.0118 

.17 

.0121 

.24 

.0148 

.49 

.0129 

.79 

959 

.0156 

.21 

.0145 

.25 

.0145 

.31 

.0148 

.42 

.0149 

.63 

.0148 

1.26 

978 

.0187 

.27 

.0174 

.32 

.0170 

.38 

.0168 

.51 

.0169 

.76 

.0169 

1.53 

1018 

.0342 

.45 

.0296 

.49 

.0290 

.61 

.0285 

.79 

.0279 

1.15 

.0255 

2.07 

1056 

.0482 

.69 

.0412 

.75 

.0392 

.88 

.0380 

1.14 

.0351 

1.56 

.0295 

2.57 

1095 

.0658 

.99 

.0530 

1.01 

.0509 

1.21 

.0472 

1.49 

.0453 

2.09 

.0313 

2.89 

1133 

.0877 

1.31 

.0698 

1.32 

.0636 

1.49 

.0574 

1.78 

.0514 

2.38 

.0346 

3.08 

A  study  was  made  of  the  precipitate  which  was  thrown  down  in  these 
solutions,  for  the  deposit  in  the  case  of  the  iso-amyl  alcohol  solutions 
was  more  abundant  than  in  the  case  of  the  deposits  in  the  other  cobalt- 
chloride  solutions.  The  solution  was  allowed  to  stand  for  two  weeks 
and  the  precipitate  filtered  off.  This  precipitate  consisted  of  blue 
needle  crystals  mixed  with  a  flocculent  scale-like  residue.  Analysis 
showed  that  in  this  flocculent  residue  there  was  present  54  per  cent 
by  weight  of  cobalt  chloride;  if  this  precipitate  was  a  compound  of  the 
cobalt  chloride  and  the  alcohol,  this  percentage  of  the  chloride  would 
indicate  that  the  compound  contained  2  molecules  of  the  chloride  to 
3  of  the  alcohol. 

The  A—  c  curves  for  the  edge  of  the  yellow-red  absorption  band, 
at  714/jju  and  724juju,  show  that  A  decreases  with  dilution.  In  the  region 
of  transparency  between  the  two  bands,  as  shown  by  the  A  —  c  curves 
for  734)uju  and  744/^u,  the  A—  c  curves  for  the  edge  of  the  infra-red 
band  show  that  A  increases  very  rapidly  with  dilution. 


The  Absorption  Coefficient  of  Solution  for  Monochromatic  Radiation.      35 


064 


700  800  900  1,000  1,100  1,200  I.300//A 

FIG.  10. — The  A-c  and  Absorption  Curves  for  Cobalt  Chloride  in  Iso-amyl  Alcohol. 

DISCUSSION  OF  RESULTS  FOR  COBALT  CHLORIDE. 

The  study  of  cobalt  chloride  in  water  and  alcoholic  solution  brings 
out  the  following  facts: 

For  the  region  of  the  spectrum  lying  on  the  long  wave-length  edge 
of  the  yellow-red  absorption  band,  the  A—  c  curves  show  that  A 
decreases  with  dilution.  The  decrease  in  A  observed  in  the  case  of  the 
aqueous  solution  is  considerable,  and  in  the  case  of  the  alcoholic  solu- 
tions this  decrease  becomes  more  and  more  marked  as  the  molecular 
complexity  of  the  alcohol  increases.  Jones  and  Anderson1  studied 
solutions  of  cobalt  chloride  in  water,  methyl  alcohol,  and  ethyl  alcohol. 
Plates  2, 4,  and  5  of  their  paper  show  that  (in  the  region  of  the  spectrum 
under  discussion)  A  decreases  with  dilution,  and  also  that  this  decrease 
is  much  more  marked  for  the  cases  of  the  alcoholic  solutions  than  for 
the  case  of  the  water  solution.  This  is  in  accord  with  the  facts  brought 
out  by  the  measurements  discussed  in  the  preceding  paragraphs.  In 
the  region  of  low  absorption  between  the  two  bands  it  is  concluded 
that  A  is  constant  with  respect  to  c.  As  has  been  mentioned  already, 
in  the  section  concerning  cobalt  chloride  in  propyl  alcohol,  the  values 
of  a  for  the  region  between  the  two  bands  are  so  small  that  the  values  of 
A  are  hi  many  cases  worthless. 

JCarnegie  Inst.  Wash.  Pub.  No.  110. 


36  Studies  on  Solution. 

In  the  region  of  wave-lengths  lying  on  the  edge  of  the  infra-red 
band,  A  experiences  deviations  from  a  constant  value,  and  again  these 
deviations  show  a  certain  regularity  concomitant  with  the  increasing 
molecular  complexity  of  the  solvent.  In  this  region  A  is  nearly  con- 
stant for  the  water  solutions,  but  increases  with  dilution  for  the  alcohol 
solutions,  the  increase  becoming  greater  as  the  molecular  weight  of 
the  alcohol  increases. 

COBALT  CHLORIDE  IN  THE  ALCOHOLS  WITH  WATER. 

The  striking  color  changes  which  take  place  when  water  is  added 
to  an  alcoholic  solution  of  cobalt  chloride  are  well  known.  Donnan 
and  Bassett1  came  to  the  conclusion  that  the  blue  color  of  certain 
solutions  of  cobalt  salts  is  due  to  the  formation  of  complex  anions  con- 
taining cobalt.  In  an  interesting  paper  by  A.  R.  Brown2  the  disap- 
pearance of  the  intense  red  absorption  band,  which  takes  place  when 
the  alcoholic  cobalt-chloride  solution  is  diluted  with  water,  is  attributed 
to  the  formation  of  a  complex  composed  of  cobalt  chloride  and  water 
molecules.  A  series  of  ethyl-alcohol  solutions  containing  increasing 
quantities  of  water  was  prepared,  and  from  the  measurements  of  a 
at  the  summit  of  the  red  absorption  band,  making  certain  assumptions 
for  which  the  original  paper  should  be  consulted,  Brown  has  calculated 
that  the  complex  contains  1  molecule  of  cobalt  chloride  associated  with 
about  15  molecules  of  water. 

The  present  work  yields  information  concerning  the  behavior  of 
the  edges  of  two  bands.  It  would  have  been  more  satisfactory  if 
the  behavior  of  the  tops  of  the  bands  could  have  been  studied.  The 
summits  of  the  bands,  however,  were  inaccessible.  Brown's  calculation 
was  applied  to  the  values  of  a  measured  for  wave-lengths  lying  on  the 
edge  of  the  red  absorption  band.  This  was  done  for  the  cases  of  the 
three  sets  of  alcoholic  mixtures  studied.  The  calculations  gave  as  a 
result  that  with  1  molecule  of  cobalt  chloride  there  was  associated  a 
large  number  of  water  molecules.  The  number  varied  from  30  to  500, 
depending  on  the  wave-length  and  the  set  of  solutions  selected  for  the 
calculation.  It  seems,  therefore,  that  one  is  not  justified  in  applying 
Brown's  calculation  to  the  values  of  a  determined  on  the  edge  of  the 
band.  It  should  be  stated,  however,  that  the  accuracy  of  the  values 
of  a  is  really  not  sufficient  to  do  complete  justice  to  the  problem. 

COBALT  CHLORIDE  IN  METHYL  ALCOHOL  WITH  WATER. 

Three  methyl-alcohol  solutions  were  prepared  containing  cobalt 
chloride  and  water.  In  table  11,  the  concentration  of  the  cobalt 
chloride,  denoted  by  c\,  was  0.5  for  each  solution.  The  concentrations 
of  the  water,  denoted  by  c2,  were  2.78,  5.55,  and  8.32.  The  values  of 
a  for  the  pure  alcohol  and  pure  water  solutions  were  taken  from  the 
work  on  cobalt  chloride  in  these  solvents. 

Uourn.  Chem.  Soc.,  81,  939  (1902).  2Proc.  Roy.  Soc.  Edinburgh,  32,  50  (1911-12). 


The  Absorption  Coefficient  of  Solution  for  Monochromatic  Radiation.      37 


The  pure-alcohol  solution  was  a  deep  purple,  changing  by  successive 
stages  to  pink  as  the  concentration  of  the  water  increased.  The  fourth 
solution,  for  which  c2  =  8.32,  was  very  nearly  the  same  color  as  the 
pure-water  solution.  These  mixtures  decomposed  upon  standing, 
in  a  manner  similar  to  the  pure-water  solutions,  yielding  a  flocculent 
precipitate. 

TABLE  11.— Cobalt  Chloride  in  Methyl  Alcohol  with  Water  (Fig.  11). 


Temp.  =20.9° 

Temp.  =18.8° 

Temp.  =18.0° 

Temp.  =17.6° 

Temp.  =18.1° 

£=10.5  mm. 

£=10.5  mm. 

£=20.2  mm. 

£  =20.2  mm. 

t  =20.0  mm. 

ci  =0.5 

ci  =0.5 

ci  =0.5 

c,  =0.5 

ci  =0.5 

length. 

C2=0 

c2=2.78 

C2  =5.55 

c2  =8.32 

c2=18.0 

a 

a—  a0 

a 

a—  a0 

a 

a—  a0 

a 

a—  cto 

d 

d-d0 

704 

0.129 

0.129 

0.0467 

0  .  0462 

0.0211 

0.0206 

0.0088 

0.0078 

724 

0.125 

0.124 

.0339 

.0334 

.0143 

.0137 

.0092 

.0087 

.0076 

.0061 

744 

.0275 

.0265 

.0128 

.0117 

.0083 

.0071 

.0078 

.0066 

.0072 

.0052 

764 

.0108 

.0101 

.0089 

.0081 

.0069 

.0061 

.0068 

.0059 

.0058 

.0038 

803 

.0069 

.0059 

.0072 

.0061 

.0063 

.0052 

.0066 

.0054 

.0074 

.0057 

842 

.0051 

.0041 

.0075 

.0064 

.0069 

.0067 

.0074 

.0061 

.0097 

.0071 

881 

.0082 

.0066 

.0102 

.0085 

.0090 

.0073 

.0089 

.0070 

.0113 

.0081 

920 

.0133 

.0081 

.0141 

.0091 

.0128 

.0078 

.0130 

.0079 

.0134 

.0088 

959 

.0139 

.0105 

.0156 

.0114 

.0145 

.0095 

.0156 

.0098 

.0303 

.0112 

978 

.0173 

.0118 

.0192 

.0130 

.0188 

.0117 

.0197 

.0119 

.0346 

.0140 

1018 

.0263 

.0179 

.0285 

.0198 

.0274 

.0184 

.0294 

.0202 

.0354 

.0215 

1056 

.0332 

.0261 

.0348 

.0277 

.0347 

.0275 

.0371 

.0300 

.0401 

.0326 

1095 

.0425 

.0374 

.0437 

.0385 

.0437 

.0383 

.0460 

.0404 

.0548 

.0464 

1134 

.0628 

.0545 

.0593 

.0506 

.0602 

.0509 

.0620 

.0525 

.0742 

.0581 

The  absorption  curves  have  not  been  plotted.  From  each  value  of 
a  has  been  subtracted  the  absorption  a0,  due  to  the  solvent.  The 
value  of  a0  has  been  calculated  from  the  known  amounts  of  water  and 
alcohol  present  in  the  solution.  The  values  of  a — a0  have  been  plotted 
as  ordinates  against  wave-lengths  as  abscissas.  These  are  the  curves 
which  appear  in  figure  11.  These  curves  show  the  well-known  sub- 
siding of  the  edge  of  the  red  absorption  band  as  the  amount  of  water 
present  in  the  alcoholic  solution  increases;  also  that  the  edge  of  the 
infra-red  band,  between  978MM  and  1,134/z/z,  is  practically  the  same  in 
methyl  alcohol  as  in  water  solutions,  and  hence  is  uninfluenced  by  the 
addition  of  water  to  the  methyl-alcohol  solution. 

COBALT  CHLORIDE  IN  ETHYL  ALCOHOL  WITH  WATER. 

Five  ethyl-alcohol  solutions  were  prepared  containing  cobalt  chloride 
and  water.  The  concentration  of  the  cobalt  chloride,  denoted  by  Ci 
in  table  12,  was  0.08  for  each  solution.  The  concentrations  of  the 
water,  denoted  by  c2,  were  1.29,  2.78,  4.16,  5.55,  and  6.94.  The  values 
of  a  for  the  pure-alcohol  and  pure-water  solutions  were  interpolated 
from  the  work  on  cobalt  chloride  in  these  solvents. 


38 


Studies  on  Solution. 


The  pure-alcohol  solution  was  a  deep  blue,  which  changed  with  the 
addition  of  water  through  a  series  of  purple  shades,  until  the  color 
became  the  pink  hue  characteristic  of  the  aqueous  cobalt-chloride 
solutions.  This  change  was  nearly  complete  for  c2  =  6.94.  These 
mixtures  decomposed  upon  standing,  yielding  a  precipitate  in  a  manner 
similar  to  the  pure-water  solutions. 


.0500 
CL-CL0 


700 


800 


900 


1.000 


—Curves  showing  the  Differences  in  Absorption  between  Solvent  and  Solutions  for 
Cobalt  Chloride  in  Mixtures  of  the  Alcohols  with  Water. 


The  Absorption  Coefficient  of  Solution  for  Monochromatic  Radiation.      39 
TABLE  12.— Cobalt  Chloride  in  Ethyl  Alcohol  with  Water  (Fig.  11). 


Temp.  =20.7° 

Temp.  =20.1° 

Temp.  =20.2° 

Temp.  =20.2° 

Temp.  =20.3° 

Temp.  =20.5° 

Temp  =20.1° 

t  =7.39  mm. 

i=20.2  mm. 

t=  20.2  mm. 

t  =20.2  mm. 

t  =20.2  mm. 

t  =20.2  mm. 

t  =20.2  mm. 

ci  =0.08 

ci  =0.08 

ci  =0.08 

ci  =0.08 

ci  =0.08 

ci  =0.08 

ci  =0.08 

Wave- 
length. 

c2=0 

c2=1.39 

c2  =2.78 

c2  =4.16 

c2  =5.55 

c2=6.94 

c8=18.0 

a 

a—  do 

a 

d-d0 

a 

a—  do 

a 

a—  a0 

a 

a—  a0 

a 

a—  a0 

a 

a—  a0 

704uu 

0.0488 

0.0488 

0.0197 

0.0196 

0.0053 

0.0052 

0.0026 

0.0024 

0.0025 

0.0015 

I  \J*T}*fA 

724 

0.0504 

0.0504 

0.0259 

0.0259 

.0107 

.0106 

.0035 

.0034 

.0016 

.0014 

.0012 

.0010 

.0027 

.0012 

744 

.0085 

.0085 

.0043 

.0042 

.0038 

.0037 

.0016 

.0015 

.0014 

.0012 

.0012 

.0010 

.0028 

.0008 

764 

.0037 

.0037 

.0016 

.0015 

.0028 

.0027 

.0011 

.0010 

.0014 

.0012 

.0012 

.0010 

.0028 

.0008 

803 

.0037 

.0037 

.0016 

.0015 

.0028 

.0027 

.0011 

.0010 

.0014 

.0012 

.0012 

.0010 

.0027 

.0010 

842 

.0027 

.0022 

.0014 

.0008 

.0026 

.0020 

.0016 

.0009 

.0020 

.0013 

.0016 

.0008 

.0039 

.0013 

881 

.0058 

.0042 

.0028 

.0012 

.0038 

.0021 

.0016 

.0009 

.0028 

.0010 

.0026 

.0008 

.0047 

.0015 

920 

.0094 

.0056 

.0053 

.0014 

.0063 

.0024 

.0049 

.0010 

.0055 

.0015 

.0049 

.0008 

.0063 

.0017 

960 

.0090 

.0062 

.0050 

.0026 

.0062 

.0026 

.0049 

.0011 

.0057 

.0013 

.0058 

.0003 

.0213 

.0022 

979 

.0106 

.0070 

.0053 

.0010 

.0072 

.0027 

.0067 

.0020 

.0074 

.0021 

.0075 

.0012 

.0234 

.0028 

1018 

.0151 

.0090 

.0111 

.0046 

.0121 

.0056 

.0104 

.0038 

.0110 

.0041 

.0109 

.0038 

.0182 

.0043 

1056 

.0237 

.0181 

.0123 

.0065 

.0113 

.0056 

.0105 

.0048 

.0109 

.0051 

.0106 

.0048 

.0133 

.0058 

1095 

.0314 

.0269 

.0170 

.0123 

.0124 

.0077 

.0114 

.0066 

.0113 

.0064 

.0113 

.0063 

.0159 

.0075 

1134 

.0543 

.0487 

.0232 

.0172 

.0190 

.0129 

.0172 

.0110 

.0164 

.0097 

.0160 

.0101 

.0256 

.0095 

The  a— a0  curves  (see  paragraph  on  cobalt  chloride  in  methyl  alcohol 
with  water,  p.  36)  show  that  as  the  amount  of  water  present  in  the 
ethyl-alcohol  solution  increases  the  absorption  at  the  edge  of  the  red 
band  becomes  less,  and  also  that  the  edge  of  the  infra-red  band  behaves 
in  a  similar  manner.  The  behavior  of  the  infra-red  band  in  the  ethyl- 
alcohol  mixture  is  thus  seen  to  differ  materially  from  that  for  the 
methyl-alcohol  mixtures. 

COBALT  CHLORIDE  IN  PROPYL  ALCOHOL  WITH  WATER. 

Four  propyl-alcohol  solutions  were  prepared  containing  cobalt 
chloride  and  water.  The  concentration  of  the  cobalt  chloride,  denoted 
by  Ci  in  table  13,  was  0.3  for  each  solution.  The  concentrations  of  the 
water,  denoted  by  c2,  were  1.11,  2.78,  5.55,  and  6.67.  The  values  of  a 
for  the  pure-alcohol  and  pure- water  solutions  were  taken  from  the  work 
on  cobalt  chloride  in  these  solvents. 

As  in  the  case  of  the  methyl-alcohol  mixtures,  the  pure  propyl- 
alcohol  solution  was  a  deep  blue,  which  changed  with  the  addition  of 
water  through  a  series  of  purples,  until  the  color  became  the  pink  hue 
characteristic  of  the  aqueous  cobalt-chloride  solutions.  This  change 
was  nearly  complete  for  c2  =  l.ll. 

The  a  — a0  curves  (see  paragraph  on  cobalt  chloride  in  methyl 
alcohol  with  water)  show  that  as  the  amount  of  water  present  in  the 
propyl-alcohol  solution  increases  the  absorption  at  the  edge  of  the  red 
band  becomes  less,  and  also  that  the  edge  of  the  infra-red  band  behaves 
in  a  similar  manner.  The  behavior  of  the  edge  of  the  infra-red  band 
is  thus  seen  to  be  much  the  same  in  the  cases  of  the  methyl-alcohol  and 
ethyl-alcohol  mixtures. 


40  Studies  on  Solution. 

TABLE  13.— Cobalt  Chloride  in  Propyl  Alcohol  with  Water  (Fig.  11}. 


Temp.  =22.1° 

Temp.  =19.6° 

Temp.  =19.8° 

Temp.  =19.8° 

Temp.  =  20.1° 

Temp.  =19.4° 

<«=10.5  mm. 

£=10.5  mm. 

£=10.5  mm. 

f  =10.5  mm. 

1=10.5  mm. 

t  =20.0  mm. 

ci  =0.3 

ci  =0.3 

ci  =0.3 

ci  =0.3 

ci  =0.3 

ci  =0.3 

Wave- 
length. 

C2=0 

C2=l.ll 

C2=2.78 

C2  =5.55 

c2  =6.67 

c2=18.0 

a 

a  -a0 

a 

a—  a0 

a 

a-a0 

a 

a  -a0 

a 

a—  a0 

a 

a  —  ao 

724uu 

0  .  0353 

0  .  0352 

0.0191 

0.0189 

0.0047 

0.0032 

•  *r*f*r* 

744 

0.0992 

0.0992 

0.0446 

0.0446 

0.0268 

0.0268 

.0086 

.0084 

.0072 

.0070 

.0045 

.0025 

764 

.0205 

.0205 

.0099 

.0099 

.0082 

.0081 

.0054 

.0052 

.0058 

.0056 

.0043 

.0023 

803 

.0142 

.0142 

.0051 

.0051 

.0061 

.0060 

.0050 

.0048 

.0058 

.0056 

.0050 

.0033 

842 

.0139 

.0135 

.0054 

.0050 

.0065 

.0060 

.0062 

.0055 

.0065 

.0058 

.0068 

.0042 

881 

.0156 

.0144 

.0075 

.0062 

.0077 

.0065 

.0072 

.0059 

.0075 

.0062 

.0078 

.0046 

920 

.0232 

.0177 

.0131 

.0076 

.0130 

.0076 

.0118 

.0063 

.0124 

.0069 

.0102 

.0056 

959 

.0254 

.0228 

.0124 

.0095 

.0128 

.0093 

.0115 

.0073 

.0128 

.0081 

.0261 

.0070 

978 

.0295 

.0269 

.0145 

.0116 

.0145 

.0110 

.0139 

.0095 

.0148 

.0097 

.0290 

.0094 

1018 

.0439 

.0384 

.0222 

.0171 

.0219 

.0160 

.0205 

.0141 

.0214 

.0149 

.0279 

.0140 

1056 

.0662 

.0614 

.0313 

.0264 

.0281 

.0222 

.0261 

.0210 

.0274 

.0223 

.0267 

.0192 

1095 

.107 

.103 

.0470 

.0432 

.0376 

.0336 

.0335 

.0293 

.0339 

.0296 

.0359 

.0275 

1134 





.0730 

.0678 

.0515 

.0459 

.0460 

.0399 

.0457 

.0393 

.0483 

.0322 

COBALT  NITRATE  IN  WATER. 

Twenty-three  solutions  were  prepared,  varying  in  concentration 
from  c  =  3.205  to  c  =  0.10.  The  A  —  c  curves  for  all  wave-lengths  show 
that  A  is  nearly  constant  for  all  concentrations.  The  A—  c  curves 
for  the  higher  values  of  A  indicate  a  very  slight  decrease  in  A  as  dilution 
proceeds.  This  decrease  is  small,  being  of  about  the  same  magnitude 
as  the  error  in  the  determination  of  A. 

TABLE  14. — Cobalt  Nitrate  in  Water  (Figs.  12  and  13). 


Temp.  =19.7° 

Temp.  =20.2° 

Temp.  =20.7° 

Temp.  =21.8° 

Temp.  =22.2° 

Temp.  =22.2° 

t  =6.36  mm. 

t  =6.36  mm. 

t  =0.36  mm. 

f  =6.30  mm. 

t  =6.36  mm. 

t  =6.36  mm. 

Wave- 

Cone. =3.205 

Cone.  =3.0 

Cone.  =2.8 

Cone.  =2.6 

Cone.  =2.4 

Cone.  =2.2 

length. 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

605w* 

0.130 

0.0405 

0.121 

0.0402 

0.104 

0.0371 

0.106 

0.0407 

0.0933 

0.0389 

0.0807 

0.0367 

645 

.112 

.0360 

.102 

.0338 

.0881 

.0314 

.0865 

.0333 

.0802 

.0334 

.0703 

.0319 

684 

.0693 

.0216 

.0645 

.0215 

.0583 

.0208 

.0563 

.0217 

.0509 

.0212 

.0453 

.0206 

724 

.0413 

.0124 

.0401 

.0129 

.0359 

.0123 

.0338 

.0124 

.0313 

.0124 

.0282 

.0122 

764 

.0325 

.0095 

.0305 

.0095 

.0287 

.0095 

.0277 

.0099 

.0249 

.0095 

.0225 

.0093 

803 

.0367 

.0109 

.0355 

.0113 

.0321 

.0109 

.0304 

.0110 

.0282 

.0110 

.0258 

.0109 

842 

.0464 

.0137 

.0438 

.0137 

.0391 

.0130 

.0371 

.0133 

.0354 

.0137 

.0325 

.0136 

881 

.0513 

.0150 

.0493 

.0154 

.0457 

.0152 

.0436 

.0156 

.0398 

.0153 

.0374 

.0155 

920 

.0597 

.0172 

.0576 

.0177 

.0530 

.0173 

.0494 

.0176 

.0459 

.0176 

.0431 

.0179 

959 

.0908 

.0223 

.0860 

.0223 

.0806 

.0219 

.0771 

.0223 

.0732 

.0225 

.0684 

.0224 

978 

.109 

.0275 

.106 

.0286 

.0978 

.0.75 

.0953 

.0287 

.0888 

.0284 

.0819 

.0279 

1018 

.150 

.0423 

.148 

.0445 

.132 

.0422 

.129 

.0442 

.118 

.0434 

.110 

.0438 

1056 

.212 

.0640 

.207 

.0665 

.183 

.0627 

.169 

.0619 

.166 

.0662 

.149 

.0643 

The  Absorption  Coefficient  of  Solution  for  Monochromatic  Radiation.      41 
TABLE  14.— Cobalt  Nitrate  in  Water  (Figs.  12  and  13}— Continued. 


Temp.  =21.3° 

Temp.  =21.4° 

Temp.  =20.7° 

Temp.  =21.1° 

Temp.  =21.8° 

Temp.  =22.8° 

<=6.36  mm 

t  =6.36  mm. 

<=10.5  mm. 

t 

=  10.5  mm. 

<=10.5  mm. 

<=10.5  mm. 

Wave- 

Cone. =2.0 

Cone.  =1.8 

Cone.  = 

1.6 

Cone.  =1.4 

Cone.  =1.2 

Cone.  =1.0 

length. 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

605^ 

0.0745 

0.0373 

0.0658 

0.0365 

0.0563 

0. 

0352 

0.0504 

0.0360 

0.0437 

0.0364 

0.0359 

0.0359 

645 

.0639 

.0320 

.0548 

.0305 

.0511 

0319 

.0434 

.0310 

.0382 

.0319 

.0312 

.0312 

684 

.0409 

.0205 

.0362 

.0201 

.0324 

0203 

.0289 

.0206 

.0241 

.0201 

.0194 

.0194 

724 

.0244 

.0115 

.0221 

.0114 

.0200 

0116 

.0173 

.0113 

.0151 

.0113 

.0128 

.0113 

764 

.0202 

.0091 

.0168 

.0082 

.0165 

0091 

.0139 

.0085 

.0124 

.0087 

.0106 

.0086 

803 

.0221 

.0102 

.0200 

.0102 

.0189 

0107 

.0148 

.0094 

.0139 

.0102 

.0111 

.0094 

842 

.0291 

.0133 

.0263 

.0132 

.0232 

0129 

.0200 

.0124 

.0176 

.0125 

.0151 

.0125 

881 

.0332 

.0150 

.0318 

.0149 

.0268 

0147 

.0236 

.0146 

.0207 

.0146 

.0176 

.0144 

920 

.0379 

.0167 

.0361 

.0175 

.0316 

. 

0169 

.0276 

.0164 

.0246 

.0167 

.0212 

.0166 

959 

.0627 

.0218 

.0581 

.0217 

.0538 

. 

0217 

.0485 

.0210 

.0438 

.0206 

.0407 

.0216 

978 

.0760 

.0277 

.0689 

.0268 

.0652 

, 

0279 

.0586 

.0271 

.0528 

.0269 

.0471 

.0265 

1018 

.0964 

.0413 

.0893 

.0419 

.0808 

, 

0418 

.0734 

.0425 

.0638 

.0416 

.0538 

.0399 

1056 

.137 

.0648 

.123 

.0642 

.108 

• 

0625 

.0923 

.0606 

.0823 

.0623 

.0697 

.0622 

Temp.  =22.7° 

Temp.  =22.9° 

Temp.  =22.5° 

Temp.  =22.2° 

Temp.  =22.3° 

Temp.  =22.5° 

<=10.5  mm. 

£=20.2  mm. 

t  =20.2  mm. 

t 

=20.2  mm. 

<=20.2  mm. 

t  =20.2  mm. 

Wave- 

Cone. =0.9 

Cone.  =0.8 

Cone.  =0.7 

Cone.  =0.6 

Cone.  =0.5 

Cone.  =0.4 

length. 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

605/uM 

0.0326 

0.0361 

0.0278 

0.0347 

0.0248 

0 

0354 

0.0206 

0.0343 

0.0177 

0.0354 

0.0146 

0.0365 

645 

.0283 

.0314 

.0255 

.0319 

.0221 

0316 

.0187 

.0315 

.0158 

.0316 

.0126 

.0315 

684 

.0184 

.0204 

.0155 

.0194 

.0139 

0199 

.0118 

.0197 

.0100 

.0204 

.0084 

.0210 

724 

.0115 

.0111 

.0107 

.0115 

.0086 

0101 

.0077 

.0103 

.0075 

.0120 

.0055 

.0100 

764 

.0092 

.0080 

.0086 

.0083 

.0075 

0079 

.0068 

.0080 

.0060 

.0080 

.0051 

.0078 

803 

.0106 

.0099 

.0097 

.0100 

.0084 

0094 

.0072 

.0092 

.0063 

.0092 

.0055 

.0095 

842 

.0139 

.0126 

.0124 

.0123 

.0110 

0120 

.0100 

.0123 

.0086 

.0120 

.0074 

.0120 

881 

.0162 

.0144 

.0146 

.0143 

.0129 

0139 

.0118 

.0143 

.0101 

.0138 

.0096 

.0160 

920 

.0205 

.0177 

.0174 

.0160 

.0155 

0156 

.0148 

.0170 

.0125 

.0158 

.0119 

.0183 

959 

.0381 

.0211 

.0356 

.0206 

.0331 

0200 

.0316 

.0208 

.0293 

.0204 

.0278 

.0218 

978 

.0457 

.0279 

.0411 

.0256 

.0381 

0250 

.0363 

.0262 

.0345 

.0278 

.0316 

.0275 

1018 

.0500 

.0401 

.0447 

.0385 

.0407 

0383 

.0372 

.0388 

.0342 

.0406 

.0294 

.0388 

1056 

.0628 

.0614 

.0576 

.0626 

.0493 

0597 

.0443 

.0613 

.0384 

.0618 

.0320 

.0613 

Temp. 

=22.5° 

Temp.  =22.6° 

Temp. 

=22.7° 

Temp.  =22.7° 

Temp.  =21.6° 

t  =20.2  mm. 

t  =20.2  mm. 

t  =20.2  mm. 

t  =20.2  mm. 

t  =20.2  mm. 

Wave-      Cone.  =0.3 

Cone.  =0.25 

Cone. 

=0.20 

Cone.  =0.15 

Cone.  =0.10 

length. 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

605MM  0.0114 

0  .  0380 

0.0092 

0.0368 

0.0074 

0.0370 

0.0060 

0.0400 

0.0043 

0.0430 

645     .0098 

.0327 

.0080 

.0320 

.0064 

.0320 

.0049 

.0333 

.0039 

.0390 

684     .0063 

.0210 

.0056 

.0224 

.0041 

.0205 

.0036 

.0240 

.0028 

.0280 

724     .0041 

.0087 

.0039 

.0096 

.0030 

.0075 

.0028 

.0087 

.0024 

.0090 

764     .0048 

.0093 

.0039 

.0076 

.0030 

.0050 

.0028 

.0053 

.0026 

.0060 

803     .0041 

.0080 

.0039 

.0088 

.0032 

.0075 

.0026 

.0060 

.0020 

.0030 

842     .0060 

.0113 

.0056 

.0120 

.0043 

.0085 

.0041 

.0100 

.0030 

.0040 

881     .0074 

.0140 

.0066 

.0136 

.0055 

.0115 

.0048 

.0107 

.0039 

.0070 

920     .0095 

.0163 

.0087 

.0164 

.0084 

.0190 

.0069 

.0153 

.0063 

.0170 

959     .0258 

.0223 

.0239 

.0192 

.0227 

.0180 

.0217 

.0173 

.0213 

.0220 

978     .0292 

.0287 

.0273 

.0268 

.0255 

.0245 

.0245 

.0260 

.0235 

.0290 

1018     .0257 

.0393 

.0235 

.0384 

.0212 

.0365 

.0194 

.0367 

.0178 

.0390 

1056     .0258 

.0610 

.0225 

.0600 

.0191 

.0630 

.0162 

.0580 

.0136 

.0610 

42 


Studies  on  Solution. 


Houstoun  has  measured  two  solutions  of  cobalt  nitrate  in  water. 
His  values  are  given  in  table  15,  for  the  sake  of  comparison. 

The  agreement,  though  poor,  is  better  than  the  agreement  in  the 
case  of  the  cobalt  chloride.  Plate  19  of  the  paper  by  Jones  and 
Anderson  shows  that  A  is  constant  with  respect  to  c  for  wave-lengths 
on  the  red  edge  of  the  yellow-green  absorption  band  of  an  aqueous 
solution  of  cobalt  nitrate. 


.0900. 


.0800  . 


.0200 


.0100  . 


1,000  UOO//A 

FIG.  12.— The  Absorption  Curves  for  Cobalt  Nitrate  in  Water. 


The  Absorpt  'on  Coefficient  of  Solution  for  Monochromatic  Radiation.      43 
TABLE  15.— A  for  Cobalt  Nitrate  in  Water. 


c=0.67 

c  =3.66 

Wave-length. 

Houstoun. 

From  table  14. 

Houstoun. 

Remarks. 

684 

0.011 

0.0198 

0.020 

720 

.010 

.0102 

.010 

750 

.010 

.0082 

.009 

No 

794 

.012 

.0091 

.012 

data  for 

850 

.013 

.0125 

.016 

comparison. 

910 

.018 

.0181 

.017 

980 

.033 

.0256 

.031 

.0600. 


.0200  _ 


.0100  _ 


.5  1.0  1.5  2.0  2.5  C 

FIG.  13.— The  A-c  Curves  for  Cobalt  Nitrate  in  Water. 
COBALT  SULPHATE  IN  WATER. 

Seventeen  solutions  were  prepared,  varying  in  concentration  from 
c  =  2.06  to  c  =  0.10.  The  A  —c  curves  show  that  throughout  the  whole 
region  of  wave-lengths  studied  A  is  a  constant  for  all  values  of  c. 


44  Studies  on  Solution. 

TABLE  16. — Cobalt  Sulphate  in  Water  (Figs.  14  and  15} . 


Temp.  =21.4° 

Temp.  =22.4° 

Temp.  =18.5° 

Temp.  =19.4° 

Temp.  =20.8° 

Temp.  =20.3° 

<=  10.5  mm. 

£=10.5  mm. 

1=10.5  mm. 

t=10.5  mm. 

<=10.5  mm. 

t  =10.5  mm. 

Wave- 

Cone. =2.06 

Cone.  =1.8 

Cone.  =1.6 

Cone.  =1.4 

Cone.  =1.2 

Cone.  =1.0 

length. 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

605/i/* 

0.0720 

0.0361 

0.0668 

0.0371 

0.0557 

0.0348 

0.0504 

0.0360 

0.0428 

0.0356 

0.0372 

0.0372 

625 

.0730 

.0361 

.0613 

.0341 

.0577 

.0360 

.0509 

.0363 

.0400 

.0334 

.0349 

.0349 

644 

.0681 

.0336 

.0652 

.0362 

.0562 

.0351 

.0484 

.0346 

.0413 

.0344 

.0348 

.0348 

664 

.0504 

.0284 

.0508 

.0282 

.0463 

.0289 

.0403 

.0288 

.0353 

.0294 

.0295 

.0395 

684 

.0507 

.0251 

.0431 

.0240 

.0375 

.0234 

.0324 

.0231 

.0283 

.0236 

.0238 

.0238 

704 

.0433 

.0201 

.0340 

.0188 

.0200 

.0181 

.0278 

.0191 

.0231 

.0184 

.0202 

.0192 

724 

.0364 

.0173 

.0300 

.0163 

.0250 

.0153 

.0236 

.0158 

.0200 

.0154 

.0174 

.0159 

744 

.0312 

.0144 

.0274 

.0141 

.0231 

.0132 

.0207 

.0133 

.0176 

.0130 

.0153 

.0133 

764 

.0285 

.0131 

.0248 

.0127 

.0215 

.0122 

.0194 

.0124 

.0162 

.0118 

.0145 

.0125 

783 

.0274 

.0127 

.0238 

.0122 

.0207 

.0118 

.0184 

.0119 

.0159 

.0117 

.0139 

.0121 

803 

.0287 

.0133 

.0252 

.0131 

.0210 

.0126 

.0192 

.0125 

.0168 

.0126 

.0142 

.0125 

823 

.0303 

.0141 

.0250 

.0134 

.0227 

.0131 

.0207 

.0135 

.0179 

.0134 

.0151 

.0133 

842 

.0331 

.0151 

.0287 

.0145 

.0257 

.0144 

.0227 

.0144 

.0200 

.0145 

.0171 

.0145 

861 

.0351 

.0160 

.0301 

.0152 

.0260 

.0151 

.0241 

.0152 

.0213 

.0154 

.0184 

.0156 

881 

.0364 

.0164 

.0323 

.0162 

.0201 

.0162 

.0254 

.0159 

.0225 

.0161 

.0189 

.0157 

001 

.0301 

.0175 

.0335 

.0166 

.0200 

.0164 

.0264 

.0163 

.0231 

.0162 

.0207 

.0171 

920 

.0422 

.0186 

.0374 

.0182 

.0330 

.0183 

.0303 

.0183 

.0261 

.0179 

.0229 

.0183 

040 

.0  02 

.0203 

.0442 

.0200 

.0380 

.0192 

.0359 

.0198 

.0324 

.0202 

.0283 

.0201 

060 

.0657 

.0230 

.0603 

.0220 

.0532 

.0213 

.0494 

.0216 

.0457 

.0222 

.0426 

.0235 

070 

.0768 

.0278 

.0703 

.0276 

.0644 

.0274 

.0608 

.0287 

.0551 

.0288 

.0488 

.0282 

008 

.0005 

.0357 

.0820 

.0355 

.0720 

.0337 

.0663 

.0344 

.0610 

.0357 

.0547 

.0366 

1018 

.105 

.0450 

.0016 

.0432 

.0838 

.0437 

.0741 

.0430 

.0656 

.0431 

.0575 

.0436 

1037 

.124 

.0563 

.110 

.0556 

.0975 

.0547 

.0867 

.0548 

.0739 

.0533 

.0628 

.0529 

Temp.  =18.5° 

Temp.  =18.7° 

Temp.  =20.5° 

Temp.  =21.2° 

Temp.  =21.3° 

Temp.  =16.3° 

<=  10.5  mm. 

<=10.5  mm. 

<=10.5  mm. 

t  =20.2  mm. 

t  =20.2  mm. 

t  =20.2  mm. 

Wave- 

Cone. =0.0 

Cone.  =0.8 

Cone.  =0.7 

Cone.  =0.6 

Cone.  =0.5 

Cone.  =0.4 

length. 

a 

A 

a 

A 

a 

A 

a 

A 

a 

\4 

a 

A 

605MM 

0.0333 

0.0370 

0.0285 

0.0356 

0.0264 

0.0377 

0.0220 

0.0367 

0.0189 

0.0378 

0.0147 

0.0368 

625 

.0314 

.0340 

.0205 

.0360 

.0259 

.0370 

.0213 

.0355 

.0180 

.0360 

.0138 

.0345 

644 

.0312 

.0347 

.0281 

.0351 

.0236 

.0337 

.0209 

.0348 

.0175 

.0350 

.0137 

.0342 

664 

.0261 

.0200 

.0241 

.0302 

.0207 

.0296 

.0183 

.0305 

.0153 

.0310 

.0121 

.0303 

684 

.0207 

.0230 

.0182 

.0227 

.0162 

.0231 

.0145 

.0241 

.0122 

.0244 

.0099 

.0248 

704 

.0173 

.0181 

.0156 

.0183 

.0131 

.0173 

.0122 

.0185 

.0100 

.0180 

.0086 

.0190 

724 

.0148 

.0148 

.0136 

.0151 

.0115 

.0143 

.0106 

.0151 

.0003 

.0156 

.0072 

.0138 

744 

.0133 

.0126 

.0121 

.0126 

.0109 

.0127 

.0099 

.0181 

.0087 

.0134 

.0072 

.0130 

764 

.0124 

.0116 

.0115 

.0110 

.0096 

.0100 

.0089 

.0115 

.0080 

.0120 

.0063 

.0108 

783 

.0121 

.0115 

.0115 

.0121 

.0096 

.0111 

.0087 

.0115 

.0078 

.0120 

.0063 

.0113 

803 

.0124 

.0110 

.0115 

.0123 

.0096 

.0113 

.0089 

.0120 

.0077 

.0120 

.0063 

.0115 

823 

.0133 

.0128 

.0121 

.0120 

.0102 

.0120 

.0097 

.0115 

.0000 

.0144 

.0069 

.0128 

842 

.0148 

.0136 

.0136 

.0138 

.0115 

.0127 

.0106 

.0133 

.0006 

.0140 

.0077 

.0128 

861 

.0150 

.0146 

.0148 

.0150 

.0124 

.0137 

.0114 

.0143 

.0101 

.0146 

.0086 

.0145 

881 

.0171 

.0155 

.0156 

.0155 

.0133 

.0144 

.0120 

.0148 

.0109 

.0154 

.0094 

.0155 

001 

.0184 

.0165 

.0168 

.0165 

.0145 

.0156 

.0135 

.0165 

.0117 

.0162 

.0103 

.0168 

020 

.0205 

.0177 

.0187 

.0176 

.0150 

.0162 

.0150 

.0173 

.0134 

.0176 

.0114 

.0170 

040 

.0257 

.0105 

.0236 

.0103 

.0218 

.0191 

.0200 

.0197 

.0182 

.0200 

.0163 

.0203 

060 

.0380 

.0220 

.0371 

.0225 

.0355 

.0234 

.0324 

.0221 

.0302 

.0222 

.0271 

.0200 

070 

.0457 

.0270 

.0428 

.0278 

.0402 

.0280 

.0376 

.0283 

.0348 

.0284 

.0316 

.0275 

008 

.0406 

.0350 

.0462 

.0351 

.0420 

.0341 

.0392 

.0351 

.0356 

.0350 

.0317 

.0340 

1018 

.0528 

.0433 

.0487 

.0435 

.0420 

.0414 

.0401 

.0437 

.0352 

.0426 

.0312 

.0433 

1037 

.0565 

.0518 

.0527 

.0536 

.0474 

.0536 

.0422 

.0538 

.0368 

.0538 

.0319 

.0550 

The  Absorption  Coefficient  of  Solution  for  Monochromatic  Radiation.      45 
TABLE  16.— Cobalt  Sulphate  in  Water  (Figs.  14  and  15}— Continued. 


Temp.  =18.2° 

Temp.  =18.3° 

Temp.  =14.3° 

Temp.  =14.6° 

t  =20.2  mm. 

£=20.2  mm. 

<=20.2  mm. 

t  =20.2  mm. 

t  =20.2  mm. 

fnnp  —  o  i 

Wave- 

Cone. =0.3 

Cone.  =0.25 

Cone.  =0.2 

Cone.  =0.15 

VyUIli/.  —  ~w.i 

length. 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

605/iji 

0.0113 

0.0377 

0.0097 

0.0388 

0.0077 

0.0385 

0.0061 

0.0407 

0.0045 

0.045 

625 

.0102 

.0340 

.0090 

.0360 

.0071 

.0355 

.0060 

.0400 

.0038 

.038 

644 

.0105 

.0350 

.0083 

.0332 

.0069 

.0345 

.0056 

.0373 

.0034 

.034 

664 

.0089 

.0297 

.0080 

.0320 

.0060 

.0300 

.0046 

.0307 

.0034 

.034 

684 

.0075 

.0250 

.0063 

.0252 

.0045 

.0225 

.0039 

.0260 

.0026 

.026 

704 

.0058 

.0160 

.0051 

.0164 

.0038 

.0140 

.0032 

.0147 

.0022 

.012 

724 

.0059 

.0147 

.0048 

.0132 

.0036 

.0105 

.0036 

.0140 

.0022 

.007 

744 

.0055 

.0117 

.0046 

.0104 

.0038 

.0090 

.0036 

.0107 

.0024 

.004 

764 

.0055 

.0117 

.0046 

.0104 

.0034 

.0070 

.0032 

.0080 

.0024 

.004 

783 

.0049 

.0103 

.0043 

.0100 

.0036 

.0090 

.0032 

.0093 

.0024 

.006 

803 

.0051 

.0113 

.0043 

.0104 

.0034 

.0085 

.0032 

.0100 

.0022 

.005 

823 

.0055 

.0123 

.0046 

.0112 

.0038 

.0100 

.0032 

.0093 

.0024 

.006 

842 

.0063 

.0123 

.0055 

.0116 

.0045 

.0095 

.0041 

.0100 

.0030 

.004 

861 

.0068 

.0133 

.0058 

.0120 

.0049 

.0105 

.0045 

.0113 

.0034 

.006 

881 

.0074 

.0140 

.0064 

.0128 

.0055 

.0115 

.0051 

.0127 

.0036 

.004 

901 

.0081 

.0150 

.0074 

.0152 

.0063 

.0135 

.0056 

.0133 

.0046 

.010 

920 

.0097 

.0170 

.0087 

.0164 

.0074 

.0140 

.0068 

.0147 

.0058 

.010 

940 

.0139 

.0190 

.0128 

.0184 

.0111 

.0145 

.0107 

.0162 

.0096 

.014 

960 

.0254 

.0210 

.0244 

.0212 

.0220 

.0145 

.0214 

.0153 

.0202 

.011 

979 

.0284 

.0260 

.0281 

.0300 

.0253 

.0235 

.0247 

.0273 

.0225 

.019 

998 

.0282 

.0337 

.0269 

.0352 

.0247 

.0330 

.0233 

.0347 

.0210 

.029 

1018 

.0259 

.0400 

.0252 

.0452 

.0225 

.0430 

.0201 

.0413 

.0177 

.038 

1037 

.0256 

.0514 

.0232 

.0533 

.0198 

.0495 

.0175 

.0507 

.0146 

.047 

Houstoun  has  measured  two  solutions  of  cobalt  sulphate  in  water. 
His  values  are  given  in  table  17,  for  the  sake  of  comparison. 

TABLE  17. — A  for  Cobalt  Sulphate  in  Water. 


... 

c=0.67 

c=2.00 

Wave-length  . 

Houstoun. 

From  table  16. 

Houstoun. 

From  table  16. 

684 

0.014 

0.0233 

0.0117 

0.0253 

720 

.005 

.0140 

.0078 

.0175 

750 

.003 

.0126 

.0057 

.0137 

794 

.007 

.0123 

.0073 

.0133 

850 

.012 

.0137 

.0136 

.0155 

910 

.012 

.0162 

.0114 

.0180 

980 

.022 

.0281 

.0211 

.0278 

Houstoun's  values  for  A  are  in  general  much  lower  than  the  values 
recorded  in  table  16.  His  values  indicate,  however,  that  A  is  a  con- 
stant with  respect  to  c  at  all  points  in  the  spectrum,  which  is  in  agree- 
ment with  the  results  of  the  present  work.  Plate  21  of  the  paper  by 


46 


Studies  on  Solution. 


.0900  _ 


.0800, 


.0700  _ 


1.4 


1.2 


1.0 


.ozoo  _ 


.0100  . 


600  700  800  900  1,000/^a. 

FIG.  14.— The  Absorption  Curves  for  Cobalt  Sulphate  in  Water. 

Jones  and  Anderson1  also  shows  the  constancy  of  A  for  wave-lengths 
on  the  long  wave-length  side  of  the  yellow-green  absorption  band  of 
an  aqueous  solution  of  cobalt  sulphate. 

Carnegie  Inst.  Wash.  Pub.  No.  110. 


The  Absorption  Coefficient  of  Solution  for  Monochromatic  Radiation.      47 


.0200  _ 


.0100  _ 


.5  1.0  1.5  C        2.0 

FIG.  15.— The  A-c  Curves  for  Cobalt  Sulphate  in  Water. 


NICKEL  CHLORIDE  IN  WATER. 

Nineteen  solutions  were  prepared,  varying  in  concentration  from 
c  =  3.945  to  c  =  0.05.  The  absorption  curves  cover  the  region  from 
550jLt/z  to  1,150/xju.  In  this  region  the  water  solutions  of  nickel  chloride 
have  an  absorption  band  in  the  red  with  its  maximum  at  744/zju,  a  region 
of  transmission  with  mhiimum  absorption  at  about  880/z/z,  and  absorp- 
tion again  beyond  this. 

The  A  —  c  curves  show  that  the  values  of  A  undergo  changes  with  c 
depending  upon  the  wave-length.  For  wave-lengths  565^  and  605juM, 
which  lie  nearly  in  the  region  of  green  transmission,  A  is  a  constant  for 
all  concentrations.  For  wave-lengths  645/z/z  and  684/x/z,  which  are  on 
the  short-wave  side  of  the  red  absorption  band,  A  increases  with  dilu- 
tion. At  the  top  of  the  band,  at  724juju,  A  is  again  constant.  For 
wave-lengths  803ju/*  to  920juju,  which  lie  on  the  long-wave  side,  the  red 
absorption  band  decreases  with  dilution.  The  result  of  these  changes 
is  to  shift  the  band  as  a  whole  towards  the  blue  with  dilution.  The 


48 


Studies  on  Solution. 


A—c  curves  for  wave-lengths  beyond  978/i/*,  on  the  edge  of  the  infra- 
red absorption  band,  show  that  A  is  a  constant  for  all  values  of  c. 

The  shift  of  the  red  band  may  also  be  seen  from  an  inspection  of  the 
absorption  curves.  This  is  seen,  not  by  looking  at  the  summit  of  the 
band,  which  remains  unchanged  in  position  of  the  minimum  of  absorp- 
tion, which  is  situated  at  920/i/i  for  c  greater  than  2.5,  and  at  881ju/z 
for  c  less  than  2.5. 


TABLE  18.— Nickel  Chloride  in  Water  (Figs.  16  and  17). 


Wave- 
length. 

Temp.  -20.3° 
t  =2.73  mm. 
Cone.  -3.045 

Temp.  -20.3° 
t  —2.73  mm. 
Cone.  —3.5 

Temp.  -20.3° 
t  —2.73  mm. 
Cone.  -3.0 

Temp.  -20.5° 
t  —2.73  mm. 
Cone.  «=2.5 

Temp.  =20.8° 
t  —2.73  mm. 
Cone.  -2.0 

Temp.  -21.5° 
t=2.73  mm. 
Cone.  =1.5 

Temp.  -21.5° 
t  =6.36  mm. 
Cone.  —1.0 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

665w* 
605 
764 
803 
842 
881 
920 
050 
078 
1018 
1056 
1005 

0.0045 

0.0243 

0.0872 

0.0240 

0.074( 

>  0.0240 

0.0568 
.176 

[).0227 
.0703 

0.0555 
.160 

0.0278 
.0798 

0.0454 
.114 
.260 
.149 
.0816 
.0523 
.0578 
.0971 
.122 
.170 
.221 
.257 

0.0303 
.0763 
.172 
.0978 
.0527 
.0327 
.0355 
.0520 
.0672 
.104 
.142 
.165 

0.0258 
.0681 
.153 
.089S 
.0512 
.0341 
.0371 
.06& 
.0822 
.118£ 
.137 
.149 

0.0258 
.0681 
.151 
.0882 
.0487 
.0309 
.0325 
.0494 
.0616 
.104 
.129 
.141 

.268 
.151 
.0963 
.0956 
.155 
.182 
.250 

.107 
.0593 
.0375 
.0362 
.0544 
.0645 
.0940 

.217 
.114 
.0666 
.0769 
.125 
.153 
.225 

.108 
.0556 
.0317 
.0362 
.0527 
.0662 
.105 

.353 
.108 
.164 
.221 
.265 

.0887 
.0404 
.0404 
.0517 
.0620 

.274 
.156 
.138 
.200 
.248 

.0774 
.0437 
.0380 
.0516 
.0648 

.206 
.121 
.115 
.172 
.213 
.200 

.0678 
.0301 
.0368 
.0510 
.0641 
.0010 

Wave- 
length. 

Temp.  -22.0° 
t  -6.36  mm. 
Cone.  -0.0 

Temp.  =20.4° 
t  —6.36  mm. 
Cone.  -0.8 

Temp.  =20.2° 
t  =6.36  mm. 
Cone.  -0.7 

Temp.  =21.0° 
<=6.36  mm. 
Cone.  -0.6 

Temp.  =21.5° 
<-  6.36  mm. 
Cone.  =0.5 

Temp.  -22.7° 
t  -6.36  mm. 
Cone.  -0.4 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

665w* 
605 
645 
684 
724 
764 
803 
842 
881 
020 
050 
078 
1018 
1056 
1005 
1183 

0.0263 
.0652 

0.0202 
.0723 

0.0225 
.0563 

0.0281 
.0704 

3.0225 
.0404 
.114 
.125 
.145 
.115 
.0638 
.0343 
.0230 
.0268 
.0522 
.0642 
.0803 
.0073 
.117 

0.0321 
.0706 
.163 
.178 
.204 
.162 
.0887 
.0453 
.0283 
.0317 
.0473 
.0623 
.0949 
.128 
.154 

0.0191 
.0453 
.0931 
.106 
.125 
.0933 
.0557 
.0313 
.0216 
.0249 
.0494 
.0598 
.0723 
.0873 
.107 

0.0318 
.0755 
.155 
.177 
.205 
.152 
.0900 
.0478 
.0307 
.0338 
.0505 
.0653 
.0973 
.133 
.164 

0.0125 
.0332 
.0787 
.0890 
.105 
.0793 
.0456 
.0268 
.0180 
.0211 
.0445 
.0527 
.0630 
.0757 
.0906 

0.0250 
.0764 
.158 
.178 
.206 
.155 
.0878 
.0484 
.0296 
.0330 
.0508 
.0642 
.0982 
.0364 
.164 

0.0125 
.0304 
.0685 
.0750 
.0850 
.0635 
.03SO 
.0230 
.0146 
.0169 
.0390 
.0459 
.0538 
.0621 
.0763 
.0894 

0.0313 
.0760 
.171 
.188 
.207 
.153 
.0908 
.0510 
.0285 
.0383 
.0498 
.0633 
.0998 
.137 
.170 
.183 

.138 
.0816 
.0470 
.0300 
.0346 
.0608 
.0775 
.100 
.121 
.145 

.151 
.0888 
.0403 
.0308 
.0333 
.0463 
.0633 
.0060 
.127 
.152 

.120 
.0750 
.0406 
.0272 
.0308 
.0580 
.0715 
.0027 
.114 
.135 

.158 
.0016 
.0475 
.0300 
.0328 
.0408 
.0636 
.0085 
.134 
.158 

The*Absorption  Coefficient  of  Solution  for  Monochromatic  Radiation.      49 
TABLE  18.— Nickel  Chloride  in  Water  (Figs.  16  and  17)— Continued. 


Temp.  =23.3° 

Temp.  =23.3° 

Temp.  =23.0° 

Temp.  =21.0° 

Temp.  =20.2° 

Temp.  -20.2° 

t  =6.36  mm. 

t  =  10.5  mm. 

t  =  10.5  mm. 

t  =20.2  mm. 

t  =20.2  mm. 

t  =20.2  mm. 

Wave- 
length. 

Cone.  =0.3 

Cone.  =0.25 

Cone.  =0.20 

Cone.  =0.15 

Cone.  =0.10 

Cone.  -0.06 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

665/i/z 

0.0102 

0.0307 

0.0079 

0.0316 

0.0062 

0.0310 

0.0038 

0.0246 

0.0036 

0.0360 

0.0022 

0.0440 

605 

.0239 

.0797 

.01S7 

.0748 

.0153 

.0765 

.0113 

.0752 

.0083 

.0830 

.0043 

.0860 

645 

.0513 

.171 

.0417 

.167 

.0345 

.173 

.0265 

.177 

.0168 

.168 

.0089 

.178 

684 

.0573 

.191 

.0457 

.183 

.0377 

.189 

.0294 

.196 

.0193 

.193 

.0099 

.198 

724 

.0645 

.210 

.0533 

.207 

.0443 

.214 

.0321 

.204 

.0225 

.210 

.0113 

.196 

764 

.0485 

.155 

.0405 

.154 

.0335 

.158 

.0243 

.149 

.0174 

.154 

.0093 

.0460 

803 

.0291 

.0913 

.0236 

.0876 

.0190 

.0865 

.0143 

.0840 

.0105 

.0890 

.0055 

.0760 

842 

.0169 

.0477 

.0139 

.0452 

.0115 

.0445 

.0086 

.0400 

.0074 

.0480 

.0043 

.0340 

881 

.0125 

.0310 

.0099 

.0268 

.0086 

.0270 

.0066 

.0226 

.0060 

.0280 

.0041 

.0180 

920 

.0146 

.0333 

.0128 

.0328 

.0106 

.0300 

.0089 

.0286 

.0078 

.0320 

.0058 

.0240 

059 

.0346 

.0517 

.0312 

.0484 

.0289 

.0490 

.0257 

.0440 

.0238 

.0470 

.0209 

.0360 

978 

.0406 

.0667 

.0368 

.0648 

.0335 

.0645 

.0302 

.0640 

.0266 

.0600 

.0232 

.0520 

1018 

.0439 

.100 

.0381 

.0968 

.0329 

.0950 

.0284 

.0967 

.0237 

.0930 

.0178 

.0780 

1056 

.0477 

.134 

.0410 

.134 

.0359 

.142 

.0277 

.135 

.0215 

.140 

.0137 

.124 

1095 

.0595 

.170 

.0504 

.168 

.0427 

.172 

.0337 

.169 

.0256 

.172 

.0160 

.152 

1133 

.0723 

.187 

.0622 

.184 

.0546 

.193 

.0436 

.184 

.0347 

.186 

.0255 

.188 

Houstoun  has  measured  two  solutions  of  nickel  chloride  in  water. 
His  values  are  shown  in  table  19  for  the  sake  of  comparison,  and  it  is 
seen  that  the  two  sets  of  values  are  not  greatly  at  variance. 

TABLE  19.— A  for  Nickel  Chloride  in  Water. 


c  =0.757 

c»4.09 

Wave-length. 

Houstoun. 

From  table  16. 

Houstoun. 

Remarks. 

684 

0.19 

0.178 

0.229 

720 

.19 

.200 

.258 

750 

.146 

.160 

.168 

794 

.071 

.090 

.101 

No  data  for 

850 

.033 

.042 

.045 

comparison. 

910 

.030 

.030 

.039 

980 

.062 

.047 

.089 

1070 

.146 

.140 

.170 

Houstoun's  values  indicate  that  A  decreases  considerably  with 
dilution,  which  is  contradictory  to  the  results  of  the  present  work. 
Plate  25  of  the  paper  by  Jones  and  Anderson1  would  seem  to  indicate 
that  A  is  very  nearly  constant,  possibly  decreasing  slightly  with  dilution, 
for  wave-lengths  on  the  short  wave-length  side  of  the  red  absorption 
band.  However,  they  state  that  the  photographic  method,  such  as 
they  used,  is  not  the  best  method  for  studying  a  band  whose  edge  is 
hazy  and  not  sharply  defined  as  is  the  case  for  this  nickel  band. 

Carnegie  Inst.  Wash.  Pub.  No.  110. 


50 


Studies  on  Solution. 


.1500 


600  700  800  900  1.000 

Fio.  16.— The  Absorption  Curves  for  Nickel  Chloride  in  Water. 


The  Absorption  Coefficient  of  Solution  for  Monochromatic  Radiation.      51 


.2000 


..     -... 


.1500 


A 

.1000 


.0500 


7Z4 


842 


1.0  2.0  3.0.  .     C      •     4.0 

FIG.  17.— The  A-c  Curves  for  Nickel  Nitrate  in  Water, 
NiCI2-6H,0  IN  ALCOHOLS. 

In  view  of  the  fact  that  the  cobalt  bands  exhibit  such  interesting 
changes  with  the  character  of  the  solvent,  an  attempt  was  made  to 
prepare  alcoholic  solutions  of  nickel  chloride.  The  dehydrated  salt, 
however,  did  not  dissolve  perceptibly  in  any  of  the  three  lower  alcohols. 


52 


Studies  on  Solution. 


In  the  case  of  the  methyl  alcohol,  a  pale  greenish-yellow  solution 
resulted  after  the  salt  had  been  allowed  to  remain  in  the  alcohol  for 
several  days.  It  is  believed  that  this  was  due  to  traces  of  water,  for  the 
addition  of  the  slightest  amount  of  water  produced  a  similar  greenish- 
yellow  solution.  The  ethyl  and  propyl  alcohols  remained  colorless  even 
after  standing  above  the  salt  for  days.  Three  solutions  of  unknown 
concentration  were  prepared  by  dropping  a  few  crystals  of  the  hydrate 
NiCk  •  6H20  into  methyl,  ethyl,  and  propyl  alcohols.  The  resulting  solu- 
tions all  showed  the  green  color  characteristic  of  the  aqueous  solution. 

TABLE  20.—NiClf6H&  in  Alcohols  (Fig.  18). 


NiCl» 
inHjO. 

NiCV6H»0 
inCHjOH. 

NiCls-6H2O 
in  C*H»OH 

NiCU-6H2O 
in  CsHjOH. 

Wave- 
length. 

Temp.  «21.5° 
t  =6.36  mm. 
Cone.  -0.5 

Temp.  -21.6° 
t  «6.36  mm. 
Cone, 
unknown. 

Temp.  =21.4° 
t  =6.36  mm. 
Cone, 
unknown. 

Temp.  -21.3 
t  =6.36  mm. 
Cone, 
unknown. 

a 

a 

a 

a 

605/iM 
615 
625 
635 
645 
655 
664 
674 
684 
694 
704 
714 
724 
734 
744 
754 
764 
774 
783 
794 
803 
813 
823 
833 
842 

0.0382 

.0593 

.0787 

0.0428 
.0489 
.0555 
.0577 
.0626 
.0624 
.0640 
.0647 
.0710 
.0720 
.0745 
.0729 
.0682 
.0668 
.0597 
.0543 
.0505 
.0442 
.0390 
.0350 
.0308 

0.0550 
.0607 
.0700 
.0740 
.0781 
.0740 
.0661 
.0621 
.0593 
.0560 
.0587 
.0607 
.0615 
.0591 
.0569 
.0533 
.0518 
.0435 
.0415 
.0413 
.0332 

0.0215 
.0257 
.0268 
.0295 
.0308 
.0282 
.0264 
.0239 
.0230 
.0230 
.0258 
.0263 
.0258 
.0258 
.0243 
.0243 
.0210 
.0195 
.0174 
.0157 
.0146 

.0851 

.0890 

.0962 

.105 

.0979 

.0793 

.0638 

.0456 



The  absorption  curves  for  these  three  solutions  show  that  the  band 
in  the  red  possesses  two  maxima.  The  absorption  curve  of  nickel 
chloride  hi  water,  c  =  0.5,  is  also  plotted  hi  figure  18  for  the  sake  of 
comparison.  The  absorption  band  for  the  aqueous  solution  has  a 
single  maximum  at  724/*ju.  In  the  curve  for  the  methyl-alcohol 
solution  this  maximum  has  been  shifted  to  744/i/i  and  there  appears  a 
second  small  maximum  at  684/x/u.  The  curve  for  the  ethyl-alcohol 
solution  shows  that  the  first  peak  has  experienced  a  still  further  shift 
towards  the  red  to  764/iju,  and  that  the  second  peak  at  684ju/z  has 


The  Absorption  Coefficient  of  Solution  for  Monochromatic  Radiation.      53 

greatly  increased  in  height.  In  the  curve  for  the  propyl-alcohol 
solution  the  positions  and  relative  height  of  the  two  peaks  are  much 
the  same  as  in  the  case  of  the  ethyl-alcohol  solution. 

In  this  connection  a  paper  by  T.  R.  Merton1  deserves  mention. 
The  absorption  curves  for  solutions  of  uranous  chloride  in  various 
solvents  were  drawn,  and  the  bands  were  shown  to  undergo  interesting 
modifications,  depending  on  the  solvent  used.  Of  course  the  cases  of 


a 

.1000 


.0500 


I 

A 


/  Curve  I  -NiCI2mH20;  C-.5 
••      n-NiC!2-6H2OinCH,OH 
"     JH-      "  "C2H5OH 


V-NiCI2-6NH3inH20 


700  800  900  1,000  1,100/t/l 

FIG.  18. — Comparison  of  the  Absorption  Curves  of  Nickel  Salts  in  Water  and  the 

Alcohols. 

the  uranous  chloride  and  the  nickel  chloride  hydrate  solutions  are  not 
exactly  comparable,  for  the  uranous  chloride  actually  does  dissolve 
in  the  solvents,  and  in  the  light  of  other  work  we  are  not  surprised  at  the 
difference  hi  the  character  of  the  bands,  but  the  nickel  chloride  goes 
into  solution  in  the  alcohols  only  in  the  presence  of  water.  Under  such 

1Proo.  Roy.  Soc.  A,  87,  138  (1912). 


54 


Studies  on  Solution. 


conditions  we  would  perhaps  not  expect  to  find  such  changes  as  have 
been  observed  above  in  the  case  of  the  nickel  band.  Possibly  similar 
examples  of  this  same  phenomenon  may  be  found. 

A  solution  of  NiCU-GNHg  hi  water  of  unknown  concentration  was 
measured,  and  its  absorption  curve  also  appears  hi  figure  18. 

NICKEL  NITRATE  IN  WATER. 

Twenty-four  solutions  were  prepared,  varying  in  concentration  from 
c  =  4.2  to  c  =  0.05.  As  was  the  case  hi  the  aqueous  nickel-chloride 
solutions,  the  A—c  curves  show  that  the  values  of  A  experience 
changes,  with  c  depending  upon  the  wave-length.  The  changes  in  the 
case  of  the  nitrate,  however,  although  similar  in  their  general  character, 
are  nowhere  so  marked  as  in  the  case  of  the  chloride.  Throughout  the 
region  from  565/i/x  to  724juju,  which  includes  the  short  wave-length  side 

TABLE  21.— Nickel  Nitrate  in  Water  {Figs.  19  and  20} . 


Wave- 
length. 

Temp.'  =20.8° 
*  =  2.73  mm. 
Cone.  =4.13 

Temp.  =  10.5° 
t  =2.73  mm. 
Cone.  =3.8 

Temp.  =  10.8° 
t  =2.73  mm. 
Cone.  =3.5 

Temp.  =  10.8° 
t  =2.73  mm. 
Cone.  =3.2 

Temp.  =  20.2° 
t  =2.73  mm. 
Cone.  =2.0 

Temp.  -  20.5° 
t  =2.73  mm. 
Cone.  =2.6 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

565MM 
605  i 
803 
842 
881 
020 
050 
078 

0,11$ 

fc«jV2 

0.0267 

0.103 

0  .-0271 

0.0060 

0.0274 

0.0820 

0.0256 

0.0758 

0.0262 

0.0678 
.215 
.248 
.128 
.0865 
.0970 
.164 
.207 

0.0260 
.0827 
.0949 
.0480 
.0320 
.0355 
.0558 
.0716 

.340 
.182 
.116 
.141 
.220 
.275 

.101 
.0511 
.0382 
.0388 
.0600 
.0726 

,306 
.162 
.102 
.132 
.204 
.257 

.0050 
.0406 
.0311 
.0306 
.0578 
.0737 

.277 
.142 
.0006 
.110 
.175 
.226 

.0948 
.0513 
.0309 
.0361 
.0538 
.0706 

.210 
.138 
.168 
.270 

.0501 
.0328 
.0305 
.0631 

.102 
.132 
.147 
.24$ 

.0407 
.0340 
.0373 
.0500 

Wave- 
length. 

Temp.  =24.8° 
t"  6.36  mm. 
Cone.  -2.3 

Temp.  =23.0° 
<=  6.36  mm. 
Cone.  =2.0 

Temp.  =24.5° 
t  =6.36  mm. 
Cone.  =1.7 

Temp.  =24.7° 
4=6.36  mm. 
Cone.  =1.4 

Temp.  =22.0° 
*  =  6.36  mm. 
Cone.  =1.1 

Temp.  =22.1° 
4=6.36  mm. 
Cone.  -1.0 

a 

A 

a 

A 

«. 

a 

A 

a 

A 

a 

A 

a 

A 

565MM 
605 
764 
803 
842 
881 
020 
050! 
078 
1018 
1056 

0.0506 

0.0250 

0.0508 

0.0254 

0.0370 

+w 

0.0233 
.0728 

0.0338 
.0017 

0.0278 
.0654 

0.0303 
.0887 

0.0275 
.0806 

0.0262 
.0749 
.158 
.0900 
.0501 
.0316 
.0362 
.0703 
.0870 
.111 
.139 

0.0262 
.0749 
.158 
.0883 
.0475 
.0284 
.0316 
.0511 
.0604 
.0971 
.131 

.200  . 
.110 
.0706 
.0810 
.130 
.165 

.0000 
.0478 
.0337 
.0336 
.0521 
.0627 

,176 
.0026 
.0601 
.0710 
.118 
.152 

.0870 
.0450 
.0285 
.0332 
.0404 
.0655 

.145 
.0705. 
.0544 
.0503 
.105 
.127 

.0868 
.0452 
.0302 
.0315 
.0505 
.0624 

.127 
.0667 
.0436 
.0510 
.0005 
.100 
.152 

.0803 
.0450 
.0288 
.0332 
.0510 
.0632 
.0086 

.0081 
.0516 
.0346 
.0406 
.0738 
.0031 
.110 
.144 

.0878 
.0446 
.0283 
.0328 
.0488 
.0659 
.105 
.133 

The  Absorption  Coefficient  of  Solution  for  Monochromatic  Radiation.      55 
TABLE  21.— Nickel  Nitrate  in  Water  (Figs.  19  and  20}— Continued. 


Temp.  =22.5° 

Temp.  =22.5° 

Temp.  =18.3° 

Temp.  =18.5° 

Temp.  =19.8° 

Temp.  =20.0° 

t  =6.36  mm. 

t  =6.36  mm. 

t  =6.36  mm. 

t  =6.36  mm. 

t  =6.36  mm. 

t  =6.36  mm. 

Wave- 

Cone. =0.9 

Cone.  =0.8 

Cone.  =0.7 

Cone.  =0.6 

Cone.  =0.5 

Cone.  =0.4 

length. 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

565/z/t 

0.0286 

0.0318 

0.0204 

0.0255 

0.0153 

0.0218 

0.0174 

0.0257 

0.0102 

0.0204 

0.0107 

0.0267 

605 

.0697 

.0775 

.0596 

.0745 

.0518 

.0740 

.0484 

.0866 

.0371 

.0742 

.0338 

.0845 

645 

.106 

.177 

.0889 

.178 

.0689 

.172 

684 

.0978 

.196 

.0786 

.195 

724 

.107 

.210 

.0868 

.213 

764 

.142 

.148 

.121 

.151 

.108 

.152 

.0950 

.155 

.0817- 

.159 

.0651 

.158 

803 

.0810 

.0881 

.0703 

.0857 

.0595 

.0826 

.0502 

.0808 

.0456 

.0878 

.0382 

.0913 

842 

.0437 

.0457 

.0386 

.0450 

.0325 

.0427 

.0281 

.0425 

.0239 

.0426 

.0211 

.0463 

881 

.0281 

.0277 

.0258 

.0283 

.0220 

.0267 

.0190 

.0263 

.0184 

.0304 

.0157 

.0313 

920 

.0338 

.0325 

.0272 

.0283 

.0258 

.0  02 

.0228 

.0310 

.0204 

.0316 

.0184 

.0345 

959 

.0641 

.0501 

.0589 

.0473 

.0512 

.0457 

.0489 

.0497 

.0446 

.0510 

.0397 

.0515 

978 

.0791 

.0628 

.0717 

.0637 

.0657 

.0644 

.0608 

.0670 

.0534 

.0656 

.0458 

.0630 

1018 

.102 

.0979 

.0956 

.102 

.0856 

.102 

.0743 

.101 

.0616 

.0954 

.0550 

.103 

1056 

.125 

.130 

.115 

.134 

.101 

.134 

.0906 

.139 

.0788 

.143 

.0636 

.140 

1095 

.152 

.161 

.132 

.156 

.117 

.156 

.111 

.171 

.0978 

.179 

.0759 

.169 

Temp.  =20.5° 

Temp.  =20.2° 

Temp.  =20.0° 

Temp.  =20.8° 

Temp.  =21.5° 

Temp.  =21.4° 

<=10.5  mm. 

t  =  10.5  mm. 

*=10.5  mm. 

t  =  10.5  mnii 

*=20.2  mm. 

t  =20.2  mm. 

Wave- 

Cone. =0.3 

Cone.  =0.25 

Cone.  =0.2 

Cone.  =0.15 

Cone.  =0.10 

Cone.  =0.05 

length. 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

565/jju 

0.0071 

0.0237 

0.0072 

0.0284 

0.0065 

0.0325 

0.0047 

0.0319 

0.0025 

0.0250 

0.0015 

0.0300 

605 

.0237 

.0790 

.0205 

.0820 

.0150 

.0750 

.0124 

.0326 

.0075 

.0750 

.0053 

.106 

645 

.0524 

.175 

.0429 

.171 

.0352 

.176 

.0265 

.176 

.0173 

.173 

.0101 

.202 

684 

.0585 

.195 

.0478 

.191 

.0386 

.193 

.0275 

.184 

.0186 

.186 

.0114 

.228 

724 

.0672 

.219 

.0556 

.216 

.0432 

.209 

.0335 

.213 

.0217 

.202 

.0134 

.240 

764 

.0496 

.159 

.0412 

.157 

.0336 

.158 

.0262 

.160 

.0167 

.147 

.0104 

.168 

803 

.0294 

.0923 

.0241 

.100 

.0195 

.0890 

.0154 

.109 

.0100 

.0830 

.0058 

.0820 

842 

.0158 

.0440 

.0139 

.0452 

.0121 

.0475 

.0089 

.0420 

.0064 

.0380 

.0046 

.0400 

881 

.0128 

.0320 

.0095 

.0242 

.0089 

.0285 

.0069 

.0253 

.0052 

.0200 

.0041 

.0040 

920 

.0148 

.0340 

.0124 

.0328 

.0109 

.0315 

.0089 

.0277 

.0071 

.0250 

.0056 

.0200 

959 

.0354 

.0543 

.0308 

.0468 

.0287 

.0480 

.0266 

.0500 

.0231 

.0400 

.0212 

.0420 

978 

.0412 

.0673 

.0369 

.0668 

.0328 

.0610 

.0302 

.0640 

.0270 

.0640 

.0238 

.0640 

1018 

.0448 

.103 

.0379 

.0960 

.0333 

.0970 

.0298 

.106 

.0229 

.0900 

.0187 

.0960 

1056 

.0502 

.142 

.0424 

.140 

.0349 

.137 

.0285 

.13 

.0203 

.128 

.0148 

.146 

1095 

.0586 

.167 

.0501 

.167 

.0423 

.160 

.0347 

.176 

.0246 

.162 

.0175 

.182 

of  the  red  absorption  band,  the  A  —  c  curves  show  that  A  is  a  constant. 
From  803/4/z  to  978/4/4,  a  region  including  the  long  wave-length  side  of 
the  red  band  and  the  region  of  low  absorption  beyond  this,  the  A—  c 
curves  show  that  A  decreases  with  dilution.  Beyond  1,018/4/4,  on  the 
edge  of  the  infra-red,  again  A  is  a  constant  for  all  values  of  c. 


56 


Studies  on  Solution. 


'500 


.0500 


600  700  800  900      ,          IjOOO  UOO/</<: 

FIG.  19. — The  Absorption  Curves  for  Nickel  Nitrate  in  Water. 


The  Absorption  Coefficient  of  Solution  for  Monochromatic  Radiation. 


Table  22  shows  the  comparison  between  Houstoun's  measurements 
and  those  of  table  21.  •***  * 

TABLE  22.- -A  for  Nickel  Nitrate 
in  Water  (Figs.  19  and  20). 


.2000 


'Wovo 

c-0.52 

length. 

Houatoun. 

From 
table  18. 

684 

0.182 

0.196 

720 

.173 

.200 

750 

.126 

.173 

794 

.065 

.0882 

850 

.032 

.0416 

910 

.024 

.0310 

980 

.058 

.0656 

1070 

.128 

.152 

959 


565 


.5  1.0  Z.O  3.0  C    4.0 

FIQ.  20.— The  A-c  Curves  for  Nickel  Nitrate  in  Water. 


58 


Studies  mi  Solution. 
TABLE  23.— Nickel  Sulphate  in  Water  (Figs.  21  and  22)i:  ££  ^ 


Wave- 
length. 

Temp.  -20.9° 
=  10  mm. 
Cone.  =2.33 

Temp.  -18.5° 
*=10mm. 
Cone.  =2.0 

Temp.  =18.6° 
f  =10  mm. 
Cone.  =1.8  ; 

Temp.  =18.6° 
«=10mm. 
Cone.  =1.6 

Temp.  =18.3° 
<=10mm. 
Cone.  =1.4 

Temp.  =19.3° 
*=10  mm. 
Cone.  =1.2 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

555/x/z 
565 
585 
605 
803 
823 
842 
861 
88* 
901 
920 
940 
959 
978 
998 

0.0391 
.0498 
.0820 

0.0195 
.0249 
.0410 

0.0335 
.0477 
.0732 

0.0186 
.0265 
.0406 

0.0290 
.0403 
.0690 
.1146 
.1462 
.1013 
.0766 
.0571 
.0511 
.0515 
.0601 
.0749 
.0991 
.1182 

0.0181 
.0252 
.0431 
.0716 
.0906 
.0621 
.0462 
.0339 
.0298 
.0298 
.0326 
.0392 
.0500 
.0610 

0.0253 
.0332 
.0611 
.1114 
.1207 
.0880 
.0662 
.0504 
.0439 
.0450 
.0524 
.0660 
.0877 
.1072 
.1225 

0.0180 
.0237 
.0437 
.0790 
.0850 
.0615 
.0454 
.0340 
.0290 
.0295 
.0341 
.0415 
.0490 
.0617 
.0748 

0.0236 
.0297 
.0505 
.0868 
.1114 
.0769 
.0575 
.0443 
.0393 
.0403 
.0461 
.0583 
.0804 
.0992 
.1121 

0.0197 
.0247 
.0421 
.0722 
.0914 
.0626 
.0456 
.0345 
.0300 
.0305 
.0346 
.0417 
.0511 
.0653 
.0782 

.  ...  . 

..... 

., 

O.L532 
.1152 
.0840 
.0741 
".0749 
:0859 
.1072 

0.0650, 
.0483; 
.  .0348 
.0304- 
.0307 
.0349 
.0391 

.1230 
.0959 
.0713 
.0627 
.0634 
.0700 
.0919 
.1207 

.0656 
..0466 
.0342 
.0298 
.0299 
.0347 
.0418 
.0507 

.1201 
.0856 
.0638 
.0578 
.0575 
.0667 
.0825 
.1130 

.0658 
.0461 
.0338 
.0303 
.0298 
.0345 
.0407 
.0521 

Wave- 
length. 

Temp.  =18.9° 
£  =  10  mm. 
Cone.  =1.0 

Temp.  =18.2° 
<=10mm. 
Cone.  =0.9 

Temp.  =18.4° 
f  =10  mm. 
Qonc.  =0.8 

Temp.  =16.0° 
<=10mm. 
Cone.  =0.7 

Temp.  =17.4° 
t—10  mm. 
Cone.  =0.6 

Temp.  =18.3° 
<  =  10  mm. 
Cone.  =0.5 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

555MM 
565 
585 
605 
625 
645 
664 
684 
704 
724 
744 
764 
783 
803 
823 
842 
861 
881 
901 
920 
940 
959 
978 
998 
1018 
1037 
1056 
1075 
1095 
1114 

0.0190 
.0250 
.0459 
.0786 

0.0190 
.0250 
.0459 
.0786 

0.0170 
.0292 
.0348 
.0732 

0.0190 
.0325 
.0397 
.0813 

0.0155 
.0188 
.0354 
.0606 

0.0194 
.0235 
.0443 
.0758 

0.0143 
.0182 
.0283 
.0545 
.0871 

0.0204 
.0260 
.0404 
.0794 
.124 

0.0111 
.0149 
.0260 
.0438 
.0681 

0.0185 
.0248 
.0433 
.0730 
.113 

0.0127 
.0149 
.0246 
.0386 
.0623 
.0829 
.0941 
.0912 
.1045 
.1033 
.0993 
.0802 
.0641 
.0474 
.0362 
.0281 
.0228 
.0201 
.0204 
.0238 
.0314 
.0474 
.0560 
.0620 
.0668 
.0725 
.0806 
.0855 
.0919 
.0971 

0.0254 
.0298 
.0492 
.0772 
.124 
.166 
.188 
.182 
.207 
.203 
.195 
.156 
.125 
.0914 
.0688 
.0510 
.0400 
.0338 
.0336 
.0384 
.0464 
.0566 
.0708 
.0878 
.106 
.125 
.146 
.157 
.167 
.173 

.1072 
.0860 
.0623 
.0455 
.0354 
.0277 
.0260 
.0250 
.0297 
.0384 
.0567 
.0683 
.0783 
.0853 

.150 
.120 
.0866 
.0624 
.0454 
.0354 
.0326 
.0306 
.0358 
.0431 
.0537 
.0681 
.0860 
.102 

.0933 
.0744 
.0544 
.0393 
.0312 
.0265 
.0218 
.0220 
.0260 
.0326 
.0501 
.0597 
.0673 
.0744 
.0807 
.0903 
.0980 

.152 
,121 
.0878 
.0625 
.0477 
.0395 
.0310 
.0307 
.0357 
.0407 
.0517 
.0652 
.0820 
.101 
.118 
.138 
.151 

.1286 
.0921 
.0653 
.0481 
.0378 
.0324 
.0335 
.0389 
.0498 
.0712 
.0859 
.0980 

.1268 
.0904 
.0635 
.0455 
.0350 
.0292 
.0299 
.0343 
.0416 
.0521 
.0653 
.0799 

.1111 
.0816 
.0596 
.0444 
.0346 
.0303 
.0308 
.0362 
.0467 
.0680 
.0810 
.0942 
.1049 

.122 
.0898 
.0642 
.0462 
.0353 
.0301 
.0302 
.0351 
.0428 
.0543 
.0670 
.0851 
.101 

.0984 
.0731 
.0547 
.0398 
.0314 
.0274 
.0279 
.0324 
.0428 
.0617 
.0728 
.0814 
.0935 

.121 
.0896 
.0661 
.0465 
.0358 
.0303 
.0304 
.0349 
.0433 
.0533 
.0653 
.0791 
.100 

The  Absorption  Coefficient  of  Solution  for  Monochromatic  Radiation.      59 
TABLE  23.— Nickel  Sulphate  in  Water  (Figs.  21  and  22)— Continued. 


Temp.  =18.2° 

Temp.  =18.9° 

Temp.  =18.9° 

Temp.  =19.5° 

Temp.  =20.4° 

Temp.  =20.6° 

t=10  mm. 

t=10  mm. 

t=W  mm. 

t  =10  mm. 

t=W  mm. 

t  =  10  mm. 

Wave- 

Cone. =0.4 

Cone.  =0.3 

Cone.  =0.2 

Cone.  =0.1 

Cone.  =0.05 

Cone.  =0.025 

length. 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

555/i/z 

0.0097 

0.0242 

0.0065 

0.0217 

0.0061 

0.0305 

0.0029 

0.0290 

0.0029 

0.0580 

0.0017 

0.0680 

565 

.0114 

.0285 

.0104 

.0347 

.0079 

.0395 

.0037 

.0370 

.0029 

.0580 

.0021 

.0840 

585 

.0204 

.0510 

.0149 

.0497 

.0114 

.0570 

.0049 

.0490 

.0033 

.0660 

.0025 

.100 

605 

.0320 

.0800 

.0250 

.0833 

.0170 

.0850 

.0083 

.0830 

.0045 

.0900 

.0025 

.100 

625 

.0502 

.126 

.0389 

.130 

.0272 

.136 

.0134 

.134 

.0076 

.152 

.0049 

.196 

645 

.0707 

.177 

.0529 

.173 

.0366 

.184 

.0179 

.179 

.0093 

.186 

.0061 

.244 

664 

.0756 

.189 

.0569 

.190 

.0395 

.198 

.0196 

.196 

.0114 

.228 

.0068 

.272 

684 

.0779 

.195 

.0586 

.195 

.0396 

.198 

.0204 

.204 

.0117 

.234 

.0068 

.272 

704 

.0838 

.207 

.0638 

.209 

.0422 

.206 

.0225 

.215 

.0130 

.240 

.0072 

.248 

724 

.0859 

.211 

.0672 

.219 

.0450 

.217 

.0238 

.223 

.0137 

.244 

.0079 

.256 

744 

.0806 

.197 

.0617 

.199 

.0425 

.202 

.0225 

.205 

.0140 

.240 

.0079 

.236 

764 

.0648 

.157 

.0500 

.160 

.0346 

.163 

.0190 

.170 

.0137 

.234 

.0068 

.192 

783 

.0505 

.122 

.0386 

.123 

.0272 

.127 

.0158 

.140 

.0107 

.178 

.0065 

.188 

803 

.0371 

.0885 

.0301 

.0947 

.0210 

.0965 

.0124 

.107 

.0079 

.124 

.0049 

.128 

823 

.0277 

.0648 

.0230 

.0707 

.0155 

.0685 

.0093 

.0750 

.0068 

.100 

.0049 

.124 

842 

.0218 

.0480 

.0185 

.0530 

.0134 

.0540 

.0083 

.0570 

.0065 

.0780 

.0049 

.0820 

861 

.0170 

.0355 

.0158 

.0433 

.0117 

.0445 

.0079 

.0510 

.0063 

.0700 

.0049 

.0840 

881 

.0158 

.0315 

.0140 

.0360 

.0107 

.0375 

.0076 

.0440 

.0060 

.0560 

.0049 

.0680 

901 

.0164 

.0320 

.0143 

.0357 

.0107 

.0355 

.0079 

.0430 

.0065 

.0580 

.0061 

.100 

920 

.0190 

.0360 

.0167 

.0403 

.0130 

.0420 

.0097 

.0510 

.0079 

.0660 

.0068 

.0880 

940 

.0258 

.0440 

.0230 

.0493 

.0176 

.0470 

.0140 

.0580 

.0121 

.0780 

.0107 

.100 

959 

.0407 

.0540 

.0355 

.0547 

.0308 

.0585 

.0253 

.0620 

.0223 

.0640 

.0215 

.0960 

978 

.0476 

.0675 

.0422 

.0720 

.0344 

.0690 

.0288 

.0820 

.0255 

.0980 

.0238 

.128 

998 

.0524 

.0858 

.0450 

.0897 

.0356 

.0875 

.0279 

.098 

.0248 

.134 

.0220 

.156 

1018 

.0560 

.105 

.0464 

.108 

.0356 

.109 

.0250 

.111 

.0207 

.136 

.0176 

.148 

1037 

.0600 

.125 

.0482 

.127 

.0360 

.130 

.0230 

.131 

.0173 

.148 

.0143 

.172 

1056 

.0656 

.145 

.0522 

.149 

.0387 

.156 

.0228 

.153 

.0161 

.172 

.0124 

.196 

1075 

.0719 

.161 

.0566 

.165 

.0408 

.169 

.0248 

.177 

.0164 

.186 

.0121 

.200 

1095 

.0804 

.180 

.0630 

.182 

.0433 

.175 

.0267 

.183 

.0185 

.202 

.0143 

.212 

1114 

.0853 

.187 

.0679 

.191 

.0497 

.196 

.0309 

.203 

.0210 

.208 

.0167 

.244 

NICKEL  SULPHATE  IN  WATER. 

Eighteen  solutions  were  prepared,  varying  in  concentration  from 
c  =  2.3  to  c  =  0.025.  The  A—  c  curves  show  that  A  is  a  constant  for 
values  of  c  greater  than  0.6,  and  for  values  of  c  less  than  0.6  that  A 
increases  with  dilution.  This  increase  in  A  for  the  more  dilute  solutions 
is  common  to  all  the  wave-lengths  studied. 

The  five  upper  strips  of  plate  28  B  of  the  paper  by  Jones  and  Ander- 
son1 indicate,  though  none  too  plainly,  that  for  wave-lengths  lying  on 
the  short  wave-length  side  of  the  red,  nickel  band  A  increases  with 
dilution  for  concentrations  below  c  =  0.5. 

Carnegie  Inst.  Wash.  Pub.  No.  110. 


60 


Studies  on  Solution. 


.0100  . 


700  800  900  1,000  MOCt*ft 

FIG.  21.— The  Absorption  Curves  for  Nickel  Sulphate  in  Water. 


The  Absorption  Coefficient  of  Soultion  for  Monochromatic  Radiation.     61 


Table  24  shows  the  comparison  between  Houstoun's  measurements 
and  those  of  table  23. 

TABLE  24.— A  for  Nickel  Sul- 
phate in  Water  (Figs .  21  and  ££) . 


.aooo 


c-0.35 

Wave- 

length. 

Houstoun. 

From 
tabl   23. 

684 

0.196 

0.195 

720 

.197 

.217 

750 

.1  1 

.190 

794 

.070 

.100 

850 

.0  4 

.0403 

<UO 

.028 

.0372 

980 

.061 

.0637 

1070 

.142 

.163 

,1500 


.0500  _V_ 


.0300  . 


823 


1 -842 


.5  1.0  1.5  C 

FIG.  22.— The  A-c  Curves  for  NickeJ  Sulphate  in  Water. 


62 


Studies  on  Solution. 
FERRIC  AMMONIUM  SULPHATE  IN  WATER. 


Twelve  solutions  were  prepared,  varying  in  concentration  from  c  =  1.0 
to  c  =  0.10.  The  absorption  curves  show  that  the  aqueous  solutions  of 
ferric  ammonium  sulphate  possess  a  broad,  rather  feeble  absorption 
band  just  beyond  the  visible  red,  whose  maximum  is  at  842/i/x,  and 
become  transparent  beyond  this.  The  transmission  curve  of  an  aque- 
ous solution  of  this  salt  has  been  roughly  drawn  in  this  region  of  the 
spectrum  by  Coblentz1  and  by  Nichols.2  The  A—  c  curves  for 

TABLE  25. — Ferric  Ammonium  Sulphate  in  Water  (Fig.  23}. 


Temp.  =20.0° 

Temp.  =20.8° 

Temp.  =21.1° 

Temp.  =21.6° 

Temp.  =22.0° 

Temp.  =22.0° 

Temp.  =18.9° 

t  =  10.5  mm. 

J  =  10.5  mm. 

<  =  10.5  mm. 

<=10.5  mm. 

t  =10.5  mm. 

£=10.5  mm. 

f  =20.2  mm. 

Wave- 

Cone. =1.0 

Cone.  =0.9 

Cone.  =0.8 

Cone.  =0.7 

Cone.  =0.6 

Cone.  =0.5 

Cone.  =0.4 

length. 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

605wi 

).0238 

0.0238 

0.0222 

0.0252 

0.0219 

0.0274 

0.0202 

0.0286 

0.0153 

0.0255 

0.0136 

0.0272 

0.0112 

0.0283 

645 

.0139 

.0139 

.0133 

.0148 

.0128 

.0160 

.0112 

.0160 

.0086 

.0143 

.0075 

.0150 

.005S 

.0145 

684 

.0133 

.0133 

.0124 

.0138 

.0124 

.0155 

.0099 

.0141 

.0082 

.0137 

.0069 

.0138 

.0055 

.0138 

724 

.0200 

.0185 

.0192 

.0189 

.0176 

.0201 

.0148 

.0190 

.0121 

.0177 

.0106 

.0182 

.008C 

.0178 

764 

.0310 

.0290 

.0288 

.0298 

.0264 

.0305 

.0230 

.0300 

.0194 

.0290 

.0159 

.0278 

.012S 

.0273 

803 

.0366 

.0349 

.0349 

.0369 

.0321 

.0380 

.0281 

.0377 

.0234 

.0362 

.0194 

.0354 

.0155 

.0345 

842 

.0394 

.0368 

.0363 

.0374 

.0339 

.0391 

.0297 

.0387 

.0252 

.0377 

.0214 

.0376 

.0174 

.0370 

881 

.0359 

.0327 

.0324 

.0324 

.0305 

.0341 

.0269 

.0338 

.0230 

.0330 

.0194 

.0324 

.0157 

.0313 

920 

.0291 

.0245 

.0264 

.0242 

.0252 

.0257 

.0231 

.0264 

.0197 

.0252 

.0168 

.0244 

.013S 

.0233 

059 

.0329 

.0138 

.0312 

.0134 

.0312 

.0151 

.0301 

.0157 

.0276 

.0142 

.0261 

.0142 

.0242 

.0128 

978 

.0323 

.0122 

.0305 

.0110 

.0303 

.0121 

.0301 

.0136 

.0283 

.0130 

.0268 

.0124 

.0253 

.0118 

1018 

.0207 

.0068 

.0197 

.0064 

.0205 

.0084 

.0197 

.0083 

.0184 

.0075 

.0173 

.0068 

.0163 

.0060 

1056 

.0121 

.0046 

.0109 

.0038 

.0124 

.0061 

.0118 

.0061 

.0106 

.0052 

.0099 

.0048 

.0093 

.0048 

1095 

.0111 

.0027 

.0102 

.0020 

.0115 

.0039 

.0111 

.0039 

.0102 

.0030 

.0099 

.0030 

.0090 

.0015 

Temp.  =19.6° 

Temp.  =20.2° 

Temp.  =20.6° 

Temp.  =21.3° 

Temp.  =21.5° 

Temp.  =21.8° 

t  =20.2  mm. 

t  =20.2  mm. 

t  =20.2  mm. 

t  =20.2  mm. 

t  =20.2  mm. 

t  =20.2  mm. 

Wave- 

Cone. =0.35 

Cone.  =0.30 

Cone.  =0.25 

Cone.  =0.20 

Cone.  =0.15 

Cone.  =0.10 

length. 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

GOow 

0.0104 

0.0297 

0.0089 

0.0297 

0.0078 

0.0312 

0.0075 

0.0375 

0.0060 

0.0400 

0.0051 

).0510 

645 

.0053 

.0152 

.0048 

.0160 

.0041 

.0164 

.0036 

.0180 

.0028 

.0186 

.0026 

.0260 

684 

.0050 

.0143 

.0045 

.0150 

.0039 

.0156 

.0034 

.0170 

.0026 

.0173 

.0022 

.0220 

724 

.0075 

.0172 

.0069 

.0180 

.0058 

.0172 

.0049 

.0170 

.0039 

.0160 

.0032 

.0170 

764 

.0115 

.0271 

.0101 

.0287 

.0089 

.0296 

.0078 

.0290 

.0060 

.0267 

.0046 

.0260 

803 

.0142 

.0357 

.0123 

.0353 

.0105 

.0352 

.0090 

.0365 

.0069 

.0347 

.0053 

.0360 

842 

.0152 

.0360 

.0138 

.0372 

.0118 

.0372 

.0101 

.0395 

.0082 

.0374 

.0058 

.0320 

881 

.0144 

.0320 

.0125 

.0310 

.0114 

.0328 

.0100 

.0340 

.0082 

.0333 

.0064 

.0320 

920 

.0124 

.0251 

.0117 

.0237 

.0107 

.0244 

.0097 

.0255 

.0083 

.0247 

.0068 

.0220 

959 

.0235 

.0126 

.0225 

.0113 

.0222 

.0124 

.0219 

.0140 

.0210 

.0120 

.0204 

.0130 

978 

.0247 

.0117 

.0237 

.0104 

.0235 

.0116 

.0231 

.0125 

.0224 

.0120 

.0221 

.0150 

1018 

.0164 

.0071 

.0158 

.0063 

.0156 

.0068 

.0150 

.0055 

.0146 

.0047 

.0147 

.0080 

1056 

.0093 

.0051 

.0087 

.0040 

.0087 

.0048 

.0083 

.0040 

.0080 

.0033 

.0080 

.0050 

1095 

.0093 

.0026 

.0089 

.0017 

.0092 

.0032 

.0089 

.0025 

.0084 

lBull.  Bureau  of  Standards,  7,  619  (1911). 


2Phys.  Rev.,  1,  1  (1896). 


The  Absorption  Coefficient  of  Solution  for  Monochromatic  Radiation.     63 


and  645/i/*,on  the  edge  of  the  band  in  the  yellow  show  that  A  increases 
with  dilution.  Throughout  the  remaining  region  from  724/*/i  to 
1,095/iju,  which  includes  the  weak  infra-red  band,  A  is  a  constant  for 
all  values  of  c. 

A 

.0400 


.0100  . 


H,0 


600  700  800  900  1,000  MOO/£/£. 

FIG.  23. — The  A-c  and  Absorption  Curves  for  Ferric  Ammonium  Sulphate  in  Water. 

An  attempt  was  made  to  carry  out  measurements  on  solutions  of 
ferric  chloride.  The  attempt  failed  because  the  precipitate  of  ferric 
hydroxide  appeared  in  such  quantities  after  the  solutions  had  remained 
in  the  cells  for  fifteen  minutes  that  any  measurements  of  a  were 
meaningless. 


64 


Studies  on  Solution. 


CHROMIUM  CHLORIDE  IN  WATER. 

Twenty-one  solutions  were  prepared,  varying  in  concentration  from 
c  =  2.06  to  c  =  0.028.  The  absorption  curves  show  that  the  edge  of  the 
green  chromium  absorption  band  at  750/zju  is  very  abrupt,  and  that  beyond 
800/x/z  a  solution,  for  which  c  =  0.557,  is  almost  as  transparent  as  water. 
The  A—  c  curves  have  been  drawn  only  3  wave-lengths  on  the  edge 
of  the  band  at  724/xju,  744/z/x,  and  764ju/x.  At  all  other  parts  of  the  spec- 
trum the  values  of  a  are  either  too  large  or  too  small  to  be  useful  for  the 
calculation  of  A.  These  three  A—  c  curves  show  that  A  decreases 


0900 


700  800  900  1,000  1,100  1.300  1,300/4^, 

FIG.  24. — The  A-c  and  Absorption  Curves  for  Chromium  Chloride  in  Water. 


The  Absorption  Coefficient  of  Solution  for  Monochromatic  Radiation.      65 


slightly  with  dilution.  Plate  56  of  the  paper  by  Jones  and  Anderson 
shows  that  for  wave-lengths  on  the  edge  of  the  green  chromium  band 
A  is  a  constant. 

TABLE  26. — Chromium  Chlw'ide  in  Water  (Fig.  24). 


Wave- 
length. 

Temp.  =19.2° 
*=2.73  mm. 
Cone.  =2.06 

Temp.  =  19.3° 
*=2.73  mm. 
Cone.  =1.8 

Temp.  =19.0° 
*=2.73  mm. 
Cone.  =1.6 

Temp.  =19.0° 
£=2.73  mm. 
Cone.  =1.4 

Temp.  =19.1° 
t  =2.73  mm. 
Cone.  =1.2 

Temp.  =19.1° 
<«=2.73mm. 
Cone.  =1.0 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

704/zju  0.355 
724        .228 
744        .113 
764        .0658 

0.171 
.107 
.0537 
.0308 

0.278 
.187 
.100 
.0501 

0.159 
.103 
.0543 
.0267 

0.287 
.169 
.0890 
.0428 

0.179 
.104 
.0543 
.0255 

0.283 
.141 
.0736 
.0380 

0.201 
.100 
.0511 
.0257 

0.235 
.124 
.0653 
.0314 

0.195 
.101 
.0526 
.0245 

0.191 
.0953 
.0476 
.0223 

0.190 
.0938 
.0456 
.0203 

Wave- 
length. 

Temp.  =19.2° 
t  =2.73  mm. 
Cone.  =0.9 

Temp.  =19.3° 
t  =2.73  mm. 
Cone.  =0.8 

Temp.  =19.5° 
«=  2.73  mm. 
Cone.  =0.7 

Temp.  =19.5° 
t  =2.73  mm. 
Cone.  =0.6 

Temp.  =19.3° 
<=10mm. 
Cone.  =0.557 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

684/i/t 
704 
724 
744 
764 

0.110 
.0550 
.0258 
.0143 
.0086 

0.198 
.0971 
.0438 
.0222 

0.191 
.0953 
.0476 
.0223 

0.211 
.104 
.0501 
.0225 

0.158 
.0759 
.0392 
.0194 

0.196 
.0930 
.0465 
.0217 

0.139 
.0666 
.0366 
.0194 

0.198 
.0930 
.0494 
.0249 

0.126 
.0619 
.0287 
.0150 

0.208 
.104 
.0445 
.0215 

Wave- 
length. 

Temp.  =20.5° 
*=10mm. 
Cone.  =0.51 

Temp.  =21.4° 
*=10mm. 
Cone.  =0.453 

Temp.  =20.5° 
<=10mm. 
Cone.  =0.397 

Temp.  =21.4° 
<=10  mm 
Cone.  =0.340 

Temp.  -20.8° 
£=10  mm. 
Cone.  *  0.288 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

684/1/1 
704 
724 
744 
764 

0.100 
.0480 
.0233 
.0130 
.0079 

0.195 
.0940 
.0426 
.0215 

0.  0919 
.0467 
.0204 
.0117 
.0064 

0.202 
.101 
.0417 
.0214 

0.0813 
.0413 
.0190 
.0114 
.0064 

0.204 
.102 
.0427 
.0236 

0.0721 
.0354 
.0164 
.0100 
.0060 

0.213 
.101 
.0438 
.0235 

0.0606 
.0290 
.0134 
.0086 
.0049 

0.213 
.0991 
.0420 
.0233 

Wave- 
length. 

Temp.  =21.3° 
i  t  =20  mm. 
Cone.  =0.227 

Temp.  =17.9° 
e=20mm. 
Cone.  =0.170 

Temp.  =18.3° 
t  =20  mm. 
Cone.  =0.1  13 

Temp.  =19.2° 
t  =20  mm. 
Cone.  =0.057 

Temp.  =19.4° 
t  =20  mm. 
Cone.  =0.028 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

684/i/i 
704 
724 
744 
764 

0.0467J 
.0234 
.01071 
.0062' 
.0043 
1 

0.206 
.0987 
.0406 
.0185 

0.0349 
.0165 
.0087 
.0055 
.0036 

0.205 
.0912 
.0424 
.0206 

0.0240 
.0119 
.0063 
.0046 
.0032 

0.213 
.0965 
.0425 
.0230 

0.0129 
.0067 
.0039 
.0032 
.0028 

0.227 
.100 
.0420 
.0210 

0.0063 
.0038 
.0028 
.0028 
.0027 

0.226 
.100 
.0464 
.0285 

66 


Studies  on  Solution. 
CHROMIUM  NITRATE  IN  WATER. 


Seventeen  solutions  were  prepared,  varying  in  concentration  from 
c  =  2.0  to  0.10.  The  general  character  of  the  absorption  for  the  nitrate 
is  the  same  as  that  of  the  chromium-chloride  solutions,  and  therefore 

TABLE  27. — Chromium  Nitrate  in  Water  (Fig.  25). 


Temp.  — 

19.3° 

Temp.  —19.5° 

Temp.  =19.7° 

Temp.  =19.7° 

Temp.  =19.7° 

Temp.  =19.8° 

t  -2.73  mm. 

•  —2.73  mm. 

t  =273  mm. 

*—  2.73  mm. 

t  s 

=2.73  ram. 

t  =2.73  mm. 

Wave- 

Cone. =2.005 

Cone.  =1.8 

Cone.  —1.6 

Cone.  =1.4 

Cone.  —1.2 

Cone.  -1.0 

length. 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

684/z/x 

0.247 

0 

123 

0.218 

0.121 

0.203 

0.127 

0.178 

0.127 

0.151 

0.126 

0.126 

0.126 

704 

.0943 

0466 

.0816 

.0447 

.0706 

.0435 

.0621 

.0436 

.0523 

.0427 

.0446 

.0436 

724 

.0314 

0149 

.0277 

.0146 

.0237 

.0139 

.0223 

.0149 

.0194 

.0149 

.0165 

.0150 

744 

.0136 

0058 

.0120 

.0056 

.0106 

.0054 

.0092 

.0051 

.0092 

.0060 

.0092 

.0072 

Temp.  — 

19.9° 

Temp.  =20.1° 

Temp.  =20.0° 

Temp.  =20.3° 

Temp.  =20.3° 

Temp.  =20.2° 

<=6.36  mm. 

t  -6.36  mm. 

/.  -6.36  mm. 

t  =6.36  mm. 

t  =6.36  mm. 

t  =6.36  mm. 

Wave 

Cone.  =0.9 

Cone.  -0.8 

Cone.  =0.7 

Cone.  =0.6 

Cone.  =0.5 

Cone.  =0.4 

length. 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

664/t/j 

0  133 

0  222 

0  111 

0  222 

0  0865 

0  216 

684 

0.107 

0. 

119 

0.0933 

0.117 

0.0786 

0.112 

.0698 

.116 

.0564 

.114 

.0476 

.1190 

704 

.0365 

0395 

.0320 

.0387 

.0276 

.0380 

.0224 

.0357 

.0195 

.0370 

.0169 

.0398 

724 

.0131 

.0129 

.0113 

.0123 

.0063 

.0069 

.0077 

.0103 

.0065 

.0100 

.0067 

.0130 

744 

.0058 

0042 

.0044 

Temp. 

=20.2° 

Temp.  -20.1°             Temp.  =20.1° 

Temp. 

=20.3° 

Temp.  =—  .-° 

t  =  10.5  mm. 

f  =  10.5  mm.                t  =  10.5  mm. 

t  =20.2  mm. 

t  —  —  .-  mm. 

Wave- 

Cone. -0.3 

Cone.  -0.25                Cone.  =0.20 

Cone. 

=0.15 

Cone.  -0.10 

length. 

a 

A 

a 

A               a              A 

a 

A 

a 

A 

664MM 

0.0663 

0.221 

0.0552 

0.221        0.0448     0.224 

0.0334 

0.223 

0.0222 

0.222 

684 

.0349 

.116 

.0297 

.119          .0238        .119 

.0178 

.119 

.0122 

.122 

704 

.0130 

.0400 

.0109 

.0396        .0089        .0395 

.0069 

.0393 

.0048 

.0380 

724 

.0044 

.0097 

.0047 

.0128        .0039        .0120 

.0032 

.0113 

.0024 

.0090 

the  absorption  curves  have  not  been  plotted.  The  A—c  curves  for 
684/zju,  704/iju,  and  724/z/z  show  that  A  decreases  slightly  with  dilution. 
This  same  decrease  in  A  with  dilution  for  wave-lengths  on  the  red  edge 
of  the  green  chromium  absorption  band  is  shown  by  Plate  58- A  of  the 
paper  by  Jones  and  Anderson. 


The  Absorption  Coefficient  of  Solution  for  Monochromatic  Radiation.      67 

CHROMIUM  SULPHATE  IN  WATER. 

Twelve  solutions  were  prepared,  varying  in  concentration  from 
c  =  0.7  to  c  =  0.025.  The  general  character  of  the  absorption  for  the 
sulphate  is  the  same  as  that  of  the  chromium-chloride  solutions,  and 
therefore  the  absorption  curves  have  not  been  plotted.  The  A—  c 
curves  for  704/jju,  724///Z,  and  744/zju,  on  the  red  edge  of  the  green 
absorption  band  show  that  in  this  region  of  the  spectrum  A  is  a 
constant  for  all  values  of  c. 


TABLE  28.— Chromium  Sulphate  in  Water  (Fig.  25). 


Temp.  =17.2° 

Temp.  =17.4° 

Temp.  =17.5° 

Temp.  =17.7° 

Temp.  =17.8° 

Temp.  =18.2° 

2=2.73  mm. 

I  =2.73  mm. 

t  =2.73  mm. 

t  =2.73  mm. 

2=2.73  mm. 

t  =2.73  mm. 

Wave- 

Cone. =0.663 

Cone.  =0.6 

Cone.  =0.5 

Cone.  =0.4 

Cone.  =0.35 

Cone.  =0.30 

length. 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

704^/1 

0.273 

0.410 

0.264 

0.438 

0.229 

0.456 

0.172 

0.432 

0.164 

0.465 

0.137 

0.453 

724 

.123 

.183 

.121 

.199 

.0978 

.193 

.0825 

.203 

.0696 

.195 

.0623 

.203 

744 

.0613 

.0891 

.0568 

.0913 

.0465 

.0890 

.0366 

.0865 

.0302 

.0806 

.0289 

.0913 

Temp.  =19.2° 

Temp.  =21.  2° 

Temp.  =18.7° 

Temp.  =18.8° 

Temp.  =18.7° 

Temp.  =18.6° 

2=6.36  mm. 

2=6.36  mm. 

2=6.36  mm. 

t  **  10.5  mm. 

2  =  10.5  mm. 

t  —20.2  mm. 

Wave- 

Cone. =0.25 

Cone.  =0.20 

Cone.  =0.15 

Cone.  =0.10 

Cone.  =0.05 

Cone.  =0.025 

length. 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

684/up 

0.122 

0.812 

0.0827 

0.827 

0  0433 

0  866 

0  0213 

0  £52 

704 

0.110 

0.436 

0.0810 

0.400 

.0642 

.421 

.0426 

.416 

.0225 

.430 

.0109 

.396 

724 

.0471 

.182 

.0390 

.188 

.0291 

.184 

.0191 

.176 

.0109 

.198 

.0055 

.160 

744 

.0220 

.0800 

.0216 

.0980 

.0135 

.0766 

.0099 

.0790 

.0058 

.0760 

.0034 

.0560 

POTASSIUM  PERMANGANATE  IN  WATER 

Eleven  solutions  were  prepared,  varying  in  concentration  from 
c  =  0.278  to  c  =  0.005.  The  absorption  curves  show  the  sharp  edge 
at  about  SOOjuju  of  the  green  absorption  band,  for  which  c  —  0.25  shows 
that  this  solution  is  nearly  as  transparent  as  pure  water. 

In  making  up  the  mother  solution  of  the  potassium  permanganate 
care  was  taken  to  prepare  the  solution  free  from  manganese  dioxide. 
The  dilutions  were  then  made,  and  the  solutions  in  the  bottles  seemed 
to  keep  well  as  long  as  they  remained  in  the  dark.  During  the  course 
of  a  measurement,  however,  the  solution  in  the  cells  became  rapidly 
permeated  with  a  black  precipitate  of  manganese  dioxide,  which  ap- 
peared to  be  caused  by  the  action  of  the  light.  Curve  I,  figure  25, 
is  for  the  fresh  solution,  for  which  c  =  0.25;  curves  II,  III,  and 
IV  are  plotted  from  measurements  made  at  30-minute  intervals  after 


68 


Studies  on  Solution. 


the  initial  filling  of  the  cells.  It  is  seen  that  the  absorption  increased 
rapidly  as  the  chemical  change  progressed.  Under  such  conditions 
the  values  of  a  were  perhaps  not  very  accurate.  All  that  could  be  done 


Cr(N03)3inH20 


684 

704 


.0200 

_ 

> 

1  —  .  —  ^^J.  — 

724 

.0100 

-  /*\^*~\  r^ 

Y             / 

•~^._, 

744 

1  

I 

A 
.4000 

.3000 
.ZDOO 
.1000 


Cr2(S04)3inH20 


704  m* 

'724 
.744 


J L 


J L 


.5   C   -7 


1.0 


1.5   C  2.0 


700 


800 


900 


1.000 


1,100 


1.200 


FIG.  25. — The  A-c  Curves  for  Chromium  Nitrate,  Chromium  Sulphate,  and  Potassium  Per- 
manganate in  Water;  the  Absorption  Curves  for  Potassium  Permanganate  in  Water. 

was  to  fill  the  cells  and  then  make  the  few  necessary  measurements  as 
quickly  as  possible.     The  A— c  curves  for  wave-lengths  744/iju,  764/*ju, 


The  Absorption  Coefficient  of  Solution  for  Monochromatic  Radiation.      69 

and  783/>tM>  the  region  on  the  long  wave-length  edge  of  the  green  absorp- 
tion band,  show  that  A  is  a  constant  with  respect  to  c  for  concentra- 
tions greater  than  c  =  0.05.  The  increase  observed  in  A  for  solutions 
of  lower  concentration  than  this  is  very  probably  due  to  the  effect  of 
decomposition. 

TABLE  29. — Potassium  Permanganate  in  Water  (Fig.  25). 


Wave- 
length. 

Temp. 
<=5 

Cone. 

=  19.5° 
mm. 
-0.278 

Temp.  =21.1° 
t  =5  mm. 
Cone.  =0.250 

Temp.  =18.8° 
t  =5  mm. 
Cone.  =0.200 

Temp.  «=  18.8° 
t  =5  mm. 
Cone.  =0.150 

Temp.  =18.9° 
t  =5  mm. 
Cone.  =0.100 

Temp.  -18.5° 
t  =5  mm. 
Cone.  =0.050 

a 

A 

a            A 

a 

A 

a 

A 

a 

A 

a 

A 

724MM 
744 
764 
783 
803 
823 

0.115 
0.481 
.0235 
.0129 
.0091 
.0067 

2.28 
0.92 
.43 
.22 

0.2228 
.0753 
.0305 
.0136 
.0091 

1.10 
0.352 
.143 
.059 

0.160 
.0571 
.0248 
.0121 
.0067 

1.05 
0.368 
.167 

0.112 
.0445 
.0214 
.0114 
.0098 

1.10 
0.425 
.196 

0.102 
.0397 
.0166 
.0083 

0.358 
.136 
.0535 

0.09 
.03 
.01 
.01 

54     0.374 
86        .117 
50        .053 
06      

Wave- 
length. 

Temp.  =18.2° 
t  =5  mm. 
Cone.  =0.025 

Temp.  =18.0° 
t  =5  mm. 
Cone.  =0.020 

Temp.  -  18.2° 
t  =5  mm. 
Cone.  =0.015 

Temp.  =17.5° 
<=5  mm. 
Cone.  =0.010 

Temp.  -17.5° 
t  =5  mm. 
Cone.  =0.005 

a 

A 

a 

A 

a 

A 

a 

A 

a 

A 

Mfyy* 
664 
684 
704 
724 
744 
764 
783 
803 
823 

0.0816 
.0657 
.0435 
.0248 
.0178 
.0121 
.0098 

0.120 
.0813 
.0481 
.0270 
.0158 
.0083 



0.1204 
.0639 
.0381 
.0187 
.0129 
.0091 
.0083 

i!77 
2.49 
1.32 
0.67 

0.167 
.0872 
.0508 
.0273 
.0121 
.0091 

0.122 
.0704 
.0381 
.0221 
.0106 
.0083 

4.31 
2.46 
1.26 

4.63 
2.44 
1.34 

4.71 
2.55 
1.38 

4.70 
3.26 
2.00 



CONCLUSION. 

The  relation  between  A,  the  molecular  light-absorption  coefficient  of 
the  solution,  denned  by  formula  2,  and  c,  the  concentration  of  the 
solution  in  gram-molecules  of  salt  per  liter  of  solution,  has  been  deter- 
mined. It  has  been  found  that  in  general  A  is  not  a  constant.  In 
certain  cases  A  decreases  with  dilution,  in  other  cases  A  increases  with 
dilution,  and  still  other  cases  as  dilution  proceeds  A  decreases  to  a 
minimum,  and  then  increases  again.  Another  possible  combination, 
namely,  that  A  should  increase  to  a  maximum  and  then  decrease,  was 
not  met  with.  The  deviations  from  a  constant  value  observed  in  A 
were  usually  comparatively  small,  except  at  certain  points  in  the 


70  Studies  on  Solution. 

spectrum  for  the  cases  of  certain  solutions.  These  points  have  been 
spoken  of  by  Houstoun1  as  "sensitive  points/7  These  sensitive  points 
have  been  found  in  general  to  be  situated  at  the  edges  of  absorption 
bands. 

At  present  there  is  no  adequate  theory  to  explain  the  facts  which 
have  been  recorded  here.  The  fact  that  A  varies  with  the  concen- 
tration has  been  probably  correctly  attributed  by  Jones  and  Anderson 
and  others  to  the  formation  of  complexes,  which  were  considered  to 
be  loose  chemical  compounds  of  molecules  of  the  salt  with  molecules 
of  the  solvent.  Undoubtedly  the  changes  in  A  with  c  observed  in  this 
investigation  may  be  explained  in  a  qualitative  manner  by  the  hypothe- 
sis of  complexes,  or  "solvates"  as  they  have  been  called;  but  before  it 
can  be  useful  for  the  interpretation  of  quantitative  data,  the  solvate 
hypothesis  must  be  couched  in  more  mathematical  terms. 

Roy.  Soc.  Edinburgh,  33,  151  (1912-13). 


CHAPTER  II. 

THE  CONDUCTIVITY  AND  VISCOSITY  OF  CERTAIN  ORGANIC  AND 
INORGANIC  SALTS  IN  FORMAMID  AND  IN  MIXTURES  OF  FORMA- 
MID  WITH  ETHYL  ALCOHOL. 


BY  P.  B.  DAVIS  AND  H.  I.  JOHNSON. 


INTRODUCTION. 

The  study  of  the  conductivity  and  viscosity  of  salts  in  formamid  as  a 
solvent  was  begun  in  the  Johns  Hopkins  Laboratory  in  1915  by  Davis, 
Putnam,  and  Jones.1  In  the  report  on  their  investigations  a  compre- 
hensive survey  is  made  of  the  work  of  previous  experimenters  on  forma- 
mid as  well  as  a  detailed  comparison  of  the  physical  and  chemical 
properties  of  this  solvent  with  those  of  water.  Their  work  comprised 
at  first  a  study  of  the  methods  available  for  obtaining  formamid  of 
sufficiently  low  specific  conductivity.  Repeated  fractional  distillation 
in  vacuo  was  finally  adopted  as  the  most  suitable  process  and  an  efficient 
vacuum  distillation  apparatus  was  devised  and  constructed.  This  appa- 
ratus and  the  scheme  of  fractionation  are  described  in  detail  in  their 
paper. 

Having  obtained  pure  formamid  in  sufficient  quantity  for  conduc- 
tivity purposes,  a  preliminary  study  was  made  of  the  conductivity,  dis- 
sociation and  viscosity  of  electrolytes  in  this  solvent.  They  found  that 
in  general  conductivity  values  are  much  lower  in  formamid  than  in 
water,  but  that  complete  dissociation  is  reached  at  a  much  lower 
dilution.  The  first  fact  is  attributed  to  the  greater  viscosity  of  forma- 
mid as  compared  with  water,  the  second  to  its  higher  dielectric  constant 
and  greater  association  factor.  From  a  study  of  the  temperature  co- 
efficients some  evidence  was  also  obtained  for  the  formation  of  solvates. 

The  viscosities  of  solutions  of  all  the  salts  studied  were  greater  than 
that  of  formamid  itself.  Even  caesium  salts,  which  produce  the  greatest 
lowering  in  the  viscosity  of  water  and  glycerol,  increase  the  viscosity  of 
formamid,  although  to  a  lesser  extent  than  the  other  salts  of  the  alkalis. 

The  present  investigation,  which  is  a  continuation  of  the  earlier  work, 
has  comprised  a  study  of  the  conductivity  and  viscosity  of  (1)  salts 
with  a  common  anion — i.  e.,  a  series  of  nitrates  of  the  inorganic  salts 
and  of  formates  of  the  organic  salts;  (2)  salts  with  a  common  cation — 
i.  e.,  the  sodium  salts  of  the  organic  acids;  (3)  a  study  of  the  behavior  of 
certain  representative  salts  in  mixtures  of  formamid  with  ethyl  alcohol. 

'Carnegie  Inst.  Wash.  Pub.  No.  230,  16. 


72  Studies  on  Solution. 

EXPERIMENTAL. 
PREPARATION  OF  THE  SOLVENTS. 

Formamid. — The  formamid  used  in  this  work  was  prepared  in  the 
same  manner  as  that  used  by  Davis  and  Putnam — i.  e.j  the  so-called 
c.  p.  material  was  subjected  to  repeated  fractionation  in  the  vacuum 
distilling  apparatus  described  by  them.  By  this  method  it  was  pos- 
sible to  obtain  formamid  of  a  specific  conductivity  comparable  to  that 
of  water  with  a  minimum  loss  of  material. 

The  conductivity  values  for  the  solvent  used  in  this  work  was  some- 
what lower  than  that  used  earlier,  ranging  from  0.7  to  1.5X10"3 
as  compared  with  2.7X10"5.  The  average  density  was  1.130  at  25°, 
the  viscosity  0.0332  at  the  same  temperature.  A  very  small  fraction, 
representing  only  about  one-tenth  of  the  original  volume,  was  obtained 
after  about  three  fractionations  more  than  required  for  preparing  the 
solvent  in  large  quantities  which  had  a  specific  conductivity  of  about 
2X10"6,  a  viscosity  of  0.03358,  and  a  density  of  1.1331.  Merry  and 
Turner1  mention  having  obtained  a  similar  fraction  by  repeated  crys- 
tallization with  a  viscosity  of  0.03359  and  density  of  1.1312. 

After  formamid  had  been  recovered  from  salts  used  in  making  about 
15  "sets"2  of  solutions,  it  was  found  by  continued  fractionation  that  a 
product  could  be  obtained  which  showed  a  specific  conductivity  of 
0.83  X  10~5  at  25°.  This  value  is  quite  comparable  with  those  obtained 
when  formamid  is  purified  from  the  commercial  product.  The  infer- 
ence drawn  from  this  observation  is  that  the  salts  do  not  alter  the  pur- 
ity of  the  solvent.  It  was  also  observed  that  formamid  upon  standing 
in  sealed  glass-stoppered  Erlenmeyer  flasks  for  a  period  of  four  months, 
June-October  1916,  in  a  dark  closet,  increased  in  specific  conductivity 
only  about  ten-fold.  The  values  observed  were  0.7  X  10~5  and  0.97  X 
10-4  at  25°. 

Formamid  with  a  specific  conductivity  of  0.70  X  10~5  at  25°  offers  no 
great  advantage  over  that  with  an  average  specific  conductivity  of 
about  1.5X  10~5  at  25°,  with  the  important  exception  of  a  lower  solvent 
correction. 

When  the  formamid  was  recovered  from  mixtures  with  ethyl  alcohol 
its  specific  conductivity  would  reach  a  value  of  the  order  of  1.5  X  10~5  at 
25°  in  about  the  same  number  of  fractionations  as  when  recovered  from 
pure  formamid  solutions,  but  on  standing  the  specific  conductivity 
soon  increased  and  in  the  course  of  3  or  4  days  became  too  large  for 
conductivity  measurements.  This  suggests  a  possible  reaction  between 
formamid  and  alcohol,  the  products  of  which  are  more  difficult  to 
remove  by  fractionation  than  the  traces  of  ammonium  formate  result- 
ing from  hydrolysis  of  pure  formamid  by  moisture  from  the  air.  Fur- 

lJourn.  Chem.  Soc.,  106,  748  (1914). 

2By  "set"  is  meant  all  the  solvent  required  for  the  solutions  of  various  dilutions. 


Conductivities  and  Viscosities  in  Formamid  and  in  Mixed  Solvents.       73 

ther  fractionation,  however,  yielded  a  product  which  maintained  a  high 
specific  conductivity  during  the  same  interval  of  time  as  the  pure 
solvent. 

Ethyl  Alcohol. — The  ethyl  alcohol  used  in  preparing  the  mixed  sol- 
vents was  obtained  by  refluxing  a  good  grade  of  commercial  alcohol 
over  lime  for  about  24  hours,  then  distilling.  The  middle  fraction 
of  about  seven-tenths  of  the  total  distillate  was  collected  and  kept  in 
receiver  similar  to  that  described  by  Lloyd  and  Pardee.  (See  Chapter 
III.)  It  had  a  mean  specific  conductivity  of  4.1X10"7  at  25°  and  a 
density  of  0.78506  to  0.78507  at  the  same  temperature. 

Mixed  Solvents. — The  mixed  solvents  containing  formamid  and 
alcohol  were  prepared  by  weighing  directly  into  glass-stoppered  flasks 
the  quantities  of  each  component  to  make  a  mixture  of  the  desired 
weight  per  cent  of  each,  all  weighings  being  reduced  to  a  vacuum. 

SALTS. 

As  in  the  earlier  work,  all  salts  used  were  carefully  recrystallized  and 
dried  to  constant  weight  at  a  suitable  temperature  depending  upon  the 
nature  of  the  salt.  In  the  case  of  calcium  nitrate,  the  salt  was  prepared 
from  the  purified  carbonate,  the  solution  evaporated  to  dryness,  and 
the  salt  heated  to  constant  weight  at  150°,  since  it  was  practically 
impossible  to  recrystallize  it.  The  aqueous  solution  showed  only 
traces  of  alkalinity. 

The  formates  and  the  sodium  salts  of  the  other  organic  acids  were 
purified  by  recrystallization  or  were  prepared  from  the  purified  acids. 
Just  before  using  they  were  dried  to  constant  weight  in  the  vacuum 
drying-oven  described  under  the  head  of  apparatus.  In  the  case  of 
all  hygroscopic  salts  the  drying  process  was  repeated  after  weighing 
out  the  required  amount  of  salt  for  the  solutions. 

SOLUTIONS. 

All  solutions  were  made  up  at  20°,  the  more  concentrated  by  direct 
weighing,  those  below  one-tenth  molar  by  dilution.  Special  precau- 
tions were  used  to  protect  both  solvent  and  solutions  from  access  of 
moisture,  the  procedure  followed  being  essentially  that  outlined  by 
Davis  and  Putnam;  25  to  50  cubic  centimeters  only  of  each  solution 
were  prepared,  as  this  amount  was  sufficient  both  for  conductivity  and 
viscosity  measurements. 

APPARATUS. 

The  conductivity  apparatus  used  was  identical  with  that  employed  in 
the  earlier  work.  The  plate  type  of  cell,  previously  described,  served 
for  measuring  the  conductivities  of  solutions  both  in  pure  formamid  and 
in  the  mixed  solvents.  The  cells  were  carefully  standardized  at  regular 
intervals. 


74 


Studies  on  Solution. 


The  viscosity  measurements  were  obtained  in  a  modified  form  of 
the  Ostwald  viscosimeter,  the  diameter  and  length  of  the  capillary 
being  adjusted  so  as  to  render  the  instrument  suitable  for  measuring 
liquids  more  viscous  than  water.  The  viscosimeters  were  calibrated 
according  to  the  more  accurate  method  proposed  by  Thole,1  using  as 
calibrating  liquids  ethyl,  propyl,  and  isobutyl  alcohols,  30,  40,  and  50 
per  cent  by  weight  mixtures  of  ethyl  alcohol  and  water  and  a  40  per 
cent  solution  of  pure  sucrose.  The  values  for  the  density  and  viscosity 
of  these  calibrating  liquids  were  obtained  from  the  data  compiled  by 
Thole,  Bingham,2  and  others  from  the  most  reliable  measurements  of 
various  investigators.  The  average  constant  obtained  for  each  instru- 
ment with  this  method  gave  somewhat  larger  values  for  the  viscosity 
of  formamid  solutions  than  when  calibrated  with  water  alone,  the  time 
of  flow  of  water  being  too  short  for  accurate  measurements — i.  e., 
less  than  100  seconds.  The  following  will  serve  as  an  example  of  the 
constants  obtained: 

VISCOSIMETER   IA. 


r/250 

D25°/4° 

tfxio-4 

Ethyl  alcohol 

0  001096 

0  78506 

1.253 

30  p  ct  ethyl  alcohol 

00218 

95967 

1.243 

40  p.  ct.  ethyl  alcohol  
40  p.  ct.  sucrose 

.00235 
005187 

.93148 
1  .  10188 

1.248 
1.244 

Av.  1.247 

All  measurements,  both  of  conductivity  and  viscosity,  were  carried 
out  in  the  thermostats  described  in  a  previous  paper,  in  which  a  con- 
stant temperature  to  within  0.01°  was  maintained. 

In  order  to  obtain  completely  anhydrous  samples  of  the  salts  studied 
a  vacuum  drying-oven  was  designed  and  constructed  with  the  aid  of 
Dr.  Pardee.  This  apparatus  consisted  of  a  tubulated  bell-jar  18  cm.  X 
24  cm.  mounted  on  a  heavy  iron  vacuum-plate.  Two  pairs  of  electrical 
connections  lead  into  the  center  of  the  plate  through  a  rubber  stopper, 
one  pair  to  a  stove  consisting  of  a  50-watt  carbon-filament  lamp  incased 
in  a  metal  chimney  open  at  the  top  and  having  a  circular  window  near 
the  bottom,  the  other  pair  leading  to  a  miniature  fan  motor  in  series 
with  an  8  candle-power  carbon  lamp  placed  on  the  outside  base.  The 
fan  maintained  circulation  within  the  oven  by  driving  the  air  through 
the  open  side  of  the  chimney,  up  around  the  lamp,  and  then  out  over 
two  dishes  containing  either  sulphuric  acid  or  phosphorus  pentoxide. 
The  material  to  be  desiccated  was  placed  in  watch  crystals  on  per- 
forated trays  set  above  the  motor  and  chimney.  The  tubular  in  the 

lJourn.  Chem.  Soc.,  105,  2009  (1914). 

»Zeit.  Phys.  Chem.  83,  644  (1913) ;  Bureau  Standards  Scientific  Paper  No.  298. 


Conductivities  and  Viscosities  in  Formamid  and  in  Mixed  Solvents.       75 

bell-jar  was  closed  with  a  rubber  stopper  carrying  the  thermometer  and 
pump  connection.  At  about  90  mm.  of  mercury  water  boils  at  49.6°. 
The  heater  maintained  a  temperature  of  65°,  the  suction  pump  a 
vacuum  of  70  to  80  mm.,  so  that  with  the  rapid  circulation  of  the  warm 
residual  air  over  the  material  and  the  drying  agent  all  traces  of  moisture 
could  be  removed  from  a  sample  with  much  greater  ease  than  in  an 
ordinary  vacuum  desiccator. 

PROCEDURE. 

Each  "set"  (i.  e.,  M/2,  M/4,  M/10,  M/50,  etc.)  of  solutions  in  pure 
formamid  were  made  up  the  day  before  the  conductivity  measurements 
were  taken,  since  experiments  showed  that  measuring  the  solutions 
on  the  same  day  they  were  prepared  did  not  increase  the  accuracy  of 
the  work.  In  the  case  of  mixed  solvents,  however,  it  was  necessary 
to  make  up  the  solutions  and  measure  them  the  same  day. 

Cells  were  read  consecutively  in  the  15°,  25°,  and  35°  baths.  This 
order  was  always  followed.  The  bridge  readings,  however,  could  be 
duplicated  for  the  more  concentrated  solutions  when  allowed  to  come 
to  temperature  again  in  the  15°  or  25°  baths. 

The  molecular  conductivity  values  were  repeated  for  a  number  of 
salts,  representing  each  series  measured,  to  within  0.5  mm.  reading 
on  the  bridge  for  all  more  concentrated  solutions.  Therefore,  consider- 
ing the  errors  in  making  up  "check"  solutions,  the  values  below  should 
be  approximately  correct. 

In  the  tables  all  conductivity  values  are  expressed  in  reciprocal  ohms 
and  are  the  molecular  conductivities  of  gram-molecular  weights  of  the 
various  salts.  These  molecular  conductivities  (/*„)  were  calculated 

VOL 

from  the  formula  ^^K-^r,  where  K  represents  the  cell  constant,  v  the 

volume  of  concentration,  R  the  resistance  in  ohms  as  measured  by  the 
rheostat,  (a)  and  (6)  the  readings  on  the  two  sides  of  the  bridge.     The 

percentage  dissociation,  a,  was  calculated  from  the  equation  a = — —  X 1 00, 

M  oo 

where  M  oo  is  the  highest  value  of  n,  obtained. 

The  temperature  coefficients  in  conductivity  units  (T)  were  derived 

by  means  of  the  formula  -~ — jr-  =  T,  in  which  jj,jt   represents    the 

t  —  t 

molecular  conductivity  at  the  higher  temperature  t,  and  /*/  at  the 
lower  temperature  t'.    The  coefficients  expressed  as  percentages  were 

T 

calculated  from  the  formula  A  =  — -• 

M 

The  values  representing  the  molecular  conductivity  in  these  tables 
are  mean  of  three  bridge-readings  involving  different  values  for  R.  The 


76 


Studies  on  Solution. 


term  V  in  the  tables  represents  the  number  of  liters  containing  a  gram- 
molecular  weight  of  the  solute.  K  expresses  the  specific  conductivity 
of  the  solvent. 

The  viscosity  data  were  calculated  from  the  formula  rj  =  K*  d-  t-, 
where  t\  presents  the  viscosity  coefficient,  k  the  constant  of  the  instru- 
ment determined  by  calibration  with  a  number  of  liquids  of  known  vis- 
cosity, d  the  density  of  the  solution  at  the  temperature  in  question, 
and  t  the  tune  of  flow  of  the  liquid  or  solution  under  investigation 
at  that  temperature.  The  fluidity  <p  is  the  reciprocal  of  the  viscos- 
ity. The  temperature  coefficients  represent  the  percentage  increase 
in  fluidity  between  the  different  temperatures  studied — i.  e.,  15°  to 
25°  and  25°  to  35°. 

TABLE  30. — Ammonium  Nitrate  in  Formamid. 


Temperature  Coefficients  of 

Conductivity. 

V 

Molecular  Conductivity. 

Dissociation. 

Per  cent. 

Conductivity 
Units. 

15° 

25° 

35° 

15° 

25° 

35° 

15-25° 

25-35° 

15-25° 

25-35° 

2 

17.45 

22.29 

27.50 

69.5 

69.2 

69.3 

0.0277 

0.0233 

0.484 

0.521 

4 

19.39 

25.08 

31.07 

77.3 

77.3 

78.4 

.0293 

.0235 

.669 

.599 

10 

22.00 

28.00 

34.75 

87.7 

87.7 

87.7 

.0273 

.0241 

.600 

.675 

50 

24.26 

30.91 

34.48 

96.7 

96.7 

97.1 

.0281 

.0244 

.665 

.757 

100 

24.34 

31.20 

38.64 

97.0 

97.0 

97.5 

.0286 

.0239 

.686 

.744 

200 

24.79 

31.76 

39.29 

98.8 

98.8 

99.2 

.0285 

.0237 

.697 

.753 

400 

25.08 

32.21 

39.59 

100.0 

100.0 

100.0 

.0284 

.0235 

.713 

.738 

tf. 

=0.94X10-*    1.24  X  10-*    1.52  X  10-* 

Mol. 

Viscosity  and  Fluidity. 

Temperature 
Coefficient  (?>). 

Z>25°/4° 

1,15° 

i?25° 

1735° 

,W       ,26' 

** 

15-25° 

25-35° 

0.5 

1  .  1436 

0.04679 

0.03515 

0.02826 

21.37     28.45 

35.39 

0.0331 

0.0244 

.25 

1.1376 

.04546 

.03409 

.02746 

22.00     29.33 

36.42 

.0332 

.0242 

.10 

1.1330 

.04474 

.03384 

.02746 

22.35     29.55 

36.42 

.0322 

.0232 

Solv. 

1.1302 

.04369 

.03298 

.02632 

22.89     30.32 

37.99 

.0325 

.0252 

Conductivities  and  Viscosities  in  Formamid  and  in  Mixed  Solvents.       77 
TABLE  31. — Potassium  Nitrate  in  Formamid. 


Temperature  Coefficients  of  Conductivity. 

V 

Molecular  Conductivity. 

Per  cent. 

Conductivity  Units. 

15° 

25° 

35° 

15-25° 

25-35° 

15-25° 

25-35° 

2 

14.08 

18 

.17 

22.72 

0.0290 

0.0250 

0.409 

0.455 

4 

16.67 

21 

.62 

26.82 

.0297 

.0240 

.495 

.520 

10 

19.04 

24 

.39 

30.30 

.0280 

.0242 

.535 

.591 

50 

21.27 

27 

.29 

33.90 

.0283 

.0242 

.602 

.661 

100 

21.90 

28 

.14 

34.85 

.0284 

.0238 

.624 

.671 

200 

22.48 

29 

.05 

36.18 

.0292 

.0245 

.657 

.713 

400 

23.70 

30.53 

37.84 

.0288 

.0239 

.683 

.731 

K=  0.945  X10~6       1.24  X  10-*       1.52  X10~5 

Mol. 

Viscosity 

and  Fluidity. 

Temperature 
Coefficients  (<p). 

Cone. 

D25°/4° 

1715° 

1725° 

7j35°          *>15° 

^25° 

*>35° 

15-25° 

25-35° 

0.5 

1  .  1570 

0.05166 

0.03858 

0.03040      19.36 

25.92 

32.89 

0.0339 

0.0269 

0.25 

1.1444 

.04836 

.03611 

.02819      20.68 

27.69 

35.47 

.0339 

.0281 

0.10 

1  .1359 

.04591 

.03450 

.02751      21.78 

28.99 

36.35 

.0331 

.0254 

Solv. 

.04369 

.03298 

.02632      22.89 

30.32 

37.99 

.0325 

.0253 

TABLE  32  — Sodium  Nitrate  in  Formamid. 


V 

Molecular  Conductivity. 

Dissociation. 

Temperature  Coefficients  of 
Conductivity. 

Per  cent. 

Conductivity 
Units. 

15° 

25° 

35° 

15° 

25° 

35° 

15-25° 

25-35° 

15-25° 

25-35° 

2 
4 
10 
50 
100 
200 
400 
800 
1600 

12.96 
15.44 
17.72 
19.38 
20.05 
20.35 
20.77 
21.30 
21.26 

16.74 
20.23 
23.32 
25.03 
26.18 
26.62 
27.14 
27.73 
27.56 
. 

21.13 
24.69 
29.72 
31.62 
33.01 
33.20 
33.98 
34.47 
34.38 
K=0.67; 

60.8 
72.4 
83.1 
90.9 
94.1 
95.5 
97.5 
100.0 

60.4 
72.9 
84.0 
90.2 
94.4 
95.9 
97.8 
100.0 

61.3 
71.6 
86.2 
91.7 
95.7 
96.3 
98.5 
100.0 

0.0291 
.0310 
.0317 
.0291 
.0305 
.0306 
.0305 
.0302 
.0295 

:io-* 

0.0260 
.0220 
.0273 
.0263 
.0260 
.0247 
.0251 
.0243 
.0247 

0.378 
.479 
.560 
.565 
.613 
.627 
.637 
.643 
.630 

0.439 
.446 
.640 
.659 
.683 
.658 
.684 
.674 
.682 

K10~5    0.87  X  10-*    1.07  X 

Mol. 
Cone. 

Viscosity  and  Fluidity. 

Temperature 
Coefficients  (<f>) 

D25°/4° 

Tjl5° 

7/25° 

7735° 

^15° 

?25° 

V>35° 

15-25° 

25-35° 

0.5 
0.25 
0.10 
Solv. 

1.1542 
1.1429 
1.1361 
1.1314 

0.05585 
.05012 
.04651 
.04403 

0.04112 
.03726 
.03509 
.03338 

0.03223 
.02972 
.02785 
.02665 

17.91 
19.95 
21.50 
22.71 

24.32 
26.84 
28.50 
29.96 

31.03 
33.65 
35.91 
37.52 

0.0358 
.0345 
.0326 
.0319 

0.0276 
.0254 
.0260 
.0252 

78 


Studies  on  Solution. 
TABLE  33. — Calcium  Nitrate  in  Formamid. 


Temperature  Coefficients  of 

Conductivity. 

Molecular  Conductivity. 

V 

Per  cent. 

Conductivity  Units. 

15° 

25° 

35° 

15-25° 

25-35° 

15-25° 

25-35° 

10 

30.44 

39.50 

49.37 

0.0297 

0.0249 

0.906 

0.987 

50 

37.80 

48.56 

60.71 

.0284 

.0250 

1.076 

.215 

100 

41.18 

52.98 

66.56 

.0286 

.0256 

1.180 

.358 

200 

42.55 

54.89 

70.13 

.0290 

.0274 

1.234 

.524 

400 

43.46 

55.90 

72.15 

.0286 

.0271 

1.244 

.625 

1600 

46.03 

58.54 

75.44 

.0272 

.0306 

1.251 

.690 

#  =  1.41X10-*    1.91  X10~5    2.34  XlO-5 

TABLE  34. — Barium  Nitrate  in  Formamid. 


Molecular  Conductivity. 

Temperature  Coefficients  of 

Conductivity. 

V 

Per  cent. 

Conductivity  Units. 

15° 

25° 

35° 

15-25° 

25-35° 

15-25° 

25-35° 

4  

20.90 

27.19 

34.14 

0.0300 

0.0255 

0.629 

0.695 

10  

28.20 

36.93 

47.08 

.0309 

.0274 

.873 

1.015 

50   ... 

36  79 

47  73 

60  77 

.0298 

.0273 

.094 

.304 

100  

39.73 

51  91 

65  05 

.  0306 

.0257 

.218 

.314 

200  

40.86 

53.16 

66.52 

.0300 

.0251 

.230 

.336 

400  

41.53 

53.94 

67.39 

.0299 

.0249 

.241 

.345 

800  

44.20 

57.51 

71.90 

.0300 

.0250 

.331 

.439 

1600  

45.24 

58.78 

74.05 

.0296 

.0259 

.354 

.527 

A"  =0.79  XlO-6 

1.99  XlO-5     1.27  XlO-5 

Viscosity  and  Fluidity. 

Temperature 
Coefficients  (<f>). 

Mol. 

Cone. 

Z>25°/4°        ij!5° 

ij25° 

7735° 

¥>15° 

^25° 

¥?35° 

15-25°    25-35° 

0.25 

1.1785      0.05815 

0.04286 

0.03393 

17.20 

22.33 

29.47 

0.0298    0.0306 

0.10 

1  .  1504        .  04903 

.03688 

.02933 

20.40 

27.11 

34.09 

.0329      .0257 

Solv. 

1.1313        .04440 

.03328 

.02651 

22.52 

30.05 

37.72 

.0334      .0255 

Conductivities  and  Viscosities  in  Formamid  and  in  Mixed  Solvents.       79 
TABLE  35. — Strontium  Nitrate  in  Formamid. 


V 

Molecular  conductivity. 

Dissociation. 

Temperature  Coefficients  of 
Conductivity. 

Per  cent. 

Conductivity 
Units. 

15° 

25° 

35° 

15° 

25° 

35° 

15-25° 

25-35° 

15-25° 

25-35° 

4 
10 
50 
100 
200 
400 
800 
1600 

22.62 
29.46 
37.73 
39.18 
41.09 
42.87 
42.94 
42.47 

30.18 
39.24 
49.73 
51.29 
53.75 
56.75 
56.91 
55.74 

37.62 
49.77 
62.99 
64.82 
67.51 
70.84 
71.38 
69.30 
K  =  l.'< 

52.6 
68.6 
87.0 
91.2 
95.6 
99.8 
100.0 

53.0 
68.5 
87.0 
90.1 
94.4 
99.7 
100.0 

52.7 
69.0 
87.4 
90.7 
94.5 
99.2 
100.0 

0.0334 
.0326 
.0319 
.0309 
.0308 
.0320 
.0325 

0.0246 
.0269 
.0265 
.0263 
.0256 
.0248 
.0254 

0.756 
.958 
1.205 
1.211 
1.266 
1.388 
1.391 

0.744 
1.053 
1.326 
1.353 
1.370 
1.409 
1.447 

J5X10-6'    1.32X10-5     1.96X10-5 

Mol. 
Cone. 

Viscosity  and  Fluidity. 

Temperature 
Coefficients  (<p). 

D25°/4° 

7jl5° 

7725° 

7/35°          *>15°        <f>25° 

<p35° 

15-25° 

25-35° 

0.25 
0.10 

Solv. 

1  .  1676 
1  .  1457 
1.1310 

0.05758 
.04947 
.04405 

0.04259 
.03686 
.03319 

0.03354      17.37      23.48 
.02956      20.21      27.13 
.02642      22.70      30.13 

29.82 
33.83 
37.85 

0.0352 
.0342 
.0327 

0.0270 
.0247 
.0253 

TABLE  36. — Rubidium  Formate  in  Formamid. 


V 

Molecular  Conductivity. 

Dissociation. 

Temperature  Coefficients  of 
Conductivity. 

Per  cent. 

Conductivity 
Units. 

15° 

25° 

35° 

15° 

25° 

35° 

15-25° 

25-35° 

15-25° 

25-35° 

10 
50 
200 
400 

Satur 
13.34 
13.44 
12.70 

ited  sok 
16.97 
17.30 
16.41 

ition. 
20.90 
21.52 
19.84 

99.3 
100.0 

98.2 
100.0 

97.1 
100.0 

0.0272 
.0287 

0.0231 
.0243 

0.363 
.386 

0.393 
.422 

r7  X  10~5    0.99  X  10~5     1  .24  X  10~5 

Viscosity  and  Fluidity. 

Mol. 

Cone. 

Z>25°/4° 

"25° 

*25° 

0.25 

1  .  1462 

0.03561 

28.08 

0.10 

1  .  1370 

.03432 

29.14 

Solv. 

1.1213 

.03286 

30.43 

80 


Studies  on  Solution. 
TABLE  37. — Ammonium  Formate  in  Formamid. 


Temperature  Coefficients  of 

Conductivity. 

V 

Molecular  Conductivity. 

Dissociation. 

Per  cent. 

Conductivity 
Units. 

15° 

25° 

35° 

15° 

25° 

35° 

15-25° 

25-35° 

15-25° 

25-35° 

10 

18.82 

24.22 

29.99 

79.9 

80.1 

80.9 

0.0287 

0.0238 

0.540 

0.577 

50 

21.86 

28.09 

34.68 

91.2 

92.9 

93.0 

.0285 

.0234 

.623 

.659 

200 

23.24 

29.82 

36.82 

97.0 

98.7 

99.4 

.0281 

.0234 

.653 

.700 

400 

23.97 

30.21 

37.04 

100.0 

100.0 

100.0 

.0260 

.0226 

.624 

.683 

A'=2.01X10~5 

2.51  X10-5     3.34  X10~5 

Viscosity  and 

Fluidity. 

Temperature 
Coefficients  (<p). 

Mol. 

Cone. 

,«•          ,25°          ,35" 

i* 

D25°/4° 

*>25° 

*>35° 

15-25° 

25-35° 

0.25 

1  .  1324 

0.04734    0.03544    0.02829 

21 

.12 

28.22 

35.35 

0.0336 

0.0253 

0.10 

1.1310 

.  04497      .  03403      .  02720 

22 

.24 

29.39 

36.76 

.0322 

.0251 

Solv. 

1.1303 

.04389      .03332      .02640 

22 

.78 

30.01 

37.88 

.0317 

.0262 

TABLE  38. — Sodium  Formate  in  Formamid. 


Y 

Molecular  Conductivity. 

Dissociation. 

Temperature  Coefficients  of 
Conductivity. 

Per  cent. 

Conductivity 
Units. 

15° 

25° 

35° 

15° 

25° 

35° 

15-25° 

25-35° 

15-25° 

25-35° 

2 
4 
10 
50 
100 
200 
400 

10.32 
12.76 
15.22 
17.35 
18.07 
18.50 
18.45 

13 

16 
19 
22 
23 
24 
24 

.67 
.48 
.91 
.64 
.61 
.15 
.01 

17.24 
21.46 
25.00 
28.44 
29.62 
30.29 
30.21 
tf=0. 

55.8 
68.9 
82.1 
93.8 
97.6 
100.0 

56.6 
68.2 
82.4 
93.8 
97.7 
100.0 

56.9 
70.8 
82.5 
93.8 
97.7 
100.0 

0.0324 
.0302 
.0309 
.0305 
.0305 
.0300 

0.0261 
.0290 
.0256 
.0255 
.0254 
.0254 

0.335 
.372 
.469 
.529 
.553 
.565 

0.357 
.498 
.509 
.580 
.601 
.614 

BX10-6 

1.  03X10-*     1.27X10-5 

Mol. 
Cone. 

Viscosity 

and  Fluidity. 

Temperature 
Coefficients  (<p). 

Z>25°/4° 

7715° 

7725° 

1735° 

,15. 

,28- 

^ 

15-25° 

25-35° 

0.50 
0.25 
0.10 
Solv. 

1  .  1469 
1  .  1393 
1  .  1345 
1.1314 

0.05869 
.05166 
.04672 
.04403 

0.04299    0 
.03812 
.03510 
.03338 

.03348 
.03037 
.02798 
.02665 

17.04 
19.36 
21.40 
22.71 

23.26 
26.23 
28.49 
29.96 

29.87 
32.93 
35.74 
37.52 

0.0365 
.0355 
.0331 
.0319 

0.0284 
.0255 
.0254 
.0252 

Conductivities  and  Viscosities  in  Formamid  and  in  Mixed  Solvents.       81 


TABLE  39. — Lithium  Formate  in  Formamid. 


Molecular  Conductivity. 

Temperature  Coefficients  of 

Conductivity. 

Dissociation. 

V 

Per  cent. 

Conductivity 

Units. 

15° 

25° 

35° 

15° 

25° 

35° 

15-25° 

25-35° 

15-25° 

25-35° 

4 

10.42 

13.47 

16.83 

56 

5 

56.6 

57.0 

0.0293 

0.0249 

0.306 

0.335 

10 

13.00 

16.82 

20.97 

70. 

9 

70.9 

71.0 

.0293 

.0246 

.381 

.416 

50 

16.53 

21.22 

26 

49 

89 

6 

89.4 

89.8 

.0283 

.0248 

.438 

.449 

100 

17.24 

22.31 

27 

56 

93 

4 

94.4 

93.4 

.0293 

.0235 

.507 

.525 

200 

17.79 

22.90 

28.35 

96. 

4 

96.3 

96.2 

.0287 

.0238 

.546 

.511 

400 

18.03 

23.25 

28.88 

97 

7 

98.1 

97.8 

.0289 

.0242 

.454 

.564 

800 

18.26 

23.51 

29.18 

99 

0 

98.9 

98.9 

.0287 

.0241 

.548 

.567 

1600 

18.44 

23.55 

29 

50 

100 

0 

100.0 

100.0 

.0289 

.0232 

.533 

.572 

K 

=0.54  X10~5 

0.71  X10~5     0.87  X10~6 

Mol. 

Viscosity  and  Fluidity. 

Temperature 
Coefficients  (<p). 

Cone. 

JD25°/4° 

rjlo0 

*?25° 

»?350 

«?15° 

?>25° 

^35° 

15-25° 

25-35° 

0.5 

1  .  1399 

0.05680 

0.04224 

0.03358 

17.61 

23.67 

29.78 

0.0344 

0.0258 

0.25  .. 

1  .  1358 

.05091 

.03787 

.03043 

19.64 

26.41 

32.86 

.0345 

.0256 

0.15 

1  .  1328 

.04637 

.03495 

.02791 

21.57 

28.61 

35.83 

.0326 

.0252 

Solv. 

1.1314 

.04403 

.03338 

.02665 

22.71 

29.96 

37.52 

.0319 

.0252 

TABLE  40. — Barium  Formate  in  Formamid. 


Temperature  Coefficients  of  Conductivity. 

V 

Molecular  Conductivity. 

Per  cent. 

Conductivity  Units. 

15° 

25° 

35° 

15-25° 

25-35° 

15-25° 

25-35° 

50 

33.35 

43.48 

53.72 

0.0296 

0.0235 

0.993 

.024 

200 

37.26 

48.87 

60.52 

.0311 

.0238 

1.161 

.165 

400 

37.94 

49.93 

61.69 

.0316 

,0236 

1.199 

.176 

800 

38.59 

50.63 

62.64 

.0311 

.0236 

1.204 

.201 

1600 

39.27 

51.67 

63.71 

.0316 

.0233 

1.240 

.204 

#=0.77XKr5     .99X10~5     1.24X10~5 

82 


Studies  on  Solution. 
TABLE  41. — Strontium  Formate  in  Formamid. 


Temperature  Coefficients  of 

Conductivity. 

V 

Molecular  Conductivity. 

Dissociation. 

Per  cent. 

Conductivity 
Unite. 

15° 

25° 

35° 

15° 

25° 

35° 

15-25° 

25-35° 

15-25° 

25-35° 

Satui 

ated  soli 

ition. 

50 

32.42 

41.54 

51.54 

77.8 

76.2 

76.8 

0.0281 

0.0241 

0.912 

1.000 

200 

37.52 

48.71 

60.78 

90.2 

89.4 

90.6 

.0298 

.0248 

1.119 

1.207 

400 

39.14 

51.60 

63.72 

94.1 

94.7 

95.2 

.0318 

.0234 

1.246 

1.212 

800 

40.37 

52.97 

65.25 

97.1 

97.2 

97.3 

.0312 

.0232 

1.260 

1.228 

1600 

41.59 

54.48 

67.05 

100.0 

100.0 

100.0 

.0310 

.0231 

1.289 

1.257 

K  =0.54  X10-5    0.71  X10-6    0.87  XlO"6 

TABLE  42. — Sodium  Benzoate  in  Formamid. 


Molecular  Conductivity. 

Dissociation. 

Temperature  Coefficients  of 

Conductivity. 

V 

Per  cent. 

Conductivity 
Unite. 

15° 

25° 

35° 

15° 

25° 

35° 

15-25° 

25-35° 

15-25° 

25-35° 

4 

9.24 

12.41 

15. 

73 

57. 

6 

60.1 

62.1 

0.0353 

0.0267 

0.317 

0.332 

8 

10.94 

14.51 

18. 

37 

68. 

2 

70.3 

72.5 

.0326 

.0266 

.357 

.386 

10 

11.40 

15.03 

19. 

15 

71. 

1 

72.8 

75.6 

.0319 

.0273 

.363 

.412 

50 

13.22 

17.54 

22. 

25 

82. 

5 

85.0 

87.8 

.0326 

.0268 

.432 

.471 

200 

14.22 

18.58 

23. 

46 

88. 

7 

90.1 

92.6 

.0306 

.0263 

.436 

.488 

400 

14.45 

18.81 

23. 

67 

90. 

2 

91.2 

93.3 

.0294 

.0259 

.436 

.486 

1600 

16.02 

20.62 

25. 

33 

100. 

0 

100.0 

100.0 

.0287 

.0223 

.460 

.471 

#=0.6X10-5    0.8  X10-6     1.06  X10-* 

Mol. 

/~V»r»/> 

Viscosity  and  Fluidity. 

Temperature 
Coefficients  (??). 

uonc. 

Z>25°/4° 

1/15° 

1/25° 

n35° 

*>15° 

<p25° 

*>35° 

15-25° 

25-35° 

0.25 

1.1392 

0.05492 

0.04047 

0.03164 

18.21 

24.71 

31.61 

0.0357 

0.0279 

0.10 

1.1342 

.04808 

.03604 

.02853 

20.80 

27.75 

35.05 

.0334 

.0263 

Solv. 

1.1295 

.  04402 

.03319 

.02678 

22.72 

30.13 

37.34 

.0326 

.0239 

Conductivities  and  Viscosities  in  Formamid  and  in  Mixed  Solvents. 
TABLE  43. — Sodium-Meta-Brom-Benzoate  in  Formamid. 


83 


F 

Molecular  Conductivity. 

Temperature  Coefficients  of 
Conductivity. 

Per  cent. 

Conductivity 
Units. 

15° 

25° 

35° 

15-25° 

25-35° 

15-25° 

25-35° 

10 
50 

10.47 
14.95 

13.92 
19.50 
K=Q. 

17.69 
24.73 
8XHT5 

0.0330 
.0313 
1.06XK 

0.0271 
.0264 
r5     1.32) 

0.345 

.477 

<io-« 

0.377 
.527 

TABLE  44. — Sodium  Metamido  Benzoate  in  Formamid. 


Molecular  Conductivity. 


15C 


25C 


35£ 


Temperature  Coefficients  of 
Conductivity. 


Per  cent. 


15-25° 


25-35° 


Conductivity 
Units. 


15-25° 


25-35° 


10. 

50. 

200. 

400. 

1600. 


10.83 
14.06 
18.31 
23.89 
56.24 


14.34 
18.53 
23.96 
31.17 
73.13 


18.20 
23.34 
30.23 
39.16 
91.30 


0.0325 
.0318 
.0308 
.0304 
.0300 


0.0269 
.0260 
.0261 
.0256 
.0254 


0.351 
.447 
.565 
.728 
.689 


0.394 
.481 
.627 
.799 

.817 


K  =0.8  X10~6  1.06.  XHT6  1.32  X10-6 


Mol. 
Cone. 


Viscosity  and  Fluidity. 


7j25c 


7735° 


Temperature 
Coefficients  (<p). 


15-25° 


25-35° 


0.10 
Solv. 


1 : 1353 
1 . 1307 


0.04884 
.04409 


0.03678 
. 03325 


0.02910 
. 02655 


20.48 
22.68 


27.19 
30.08 


34.36 
37.66 


0.0328 
.0326 


0.0264 
.0252 


84 


Studies  on  Solution. 
TABLE  45. — Sodium-Dinitro-Benzoate  (1,  3,  J)  in  Formamid. 


Molecular  Conductivity. 


lf)c 


35= 


Temperature  Coefficients  of 
Conductivity. 


Per  cent. 


15-25°      25-35 


Conductivity 
Units. 


15-25°    25-35° 


10. 

50. 

200. 

400. 

1600. 


10.43 
13.09 
16.18 
21.64 
47.08 
K 


13.95 
17.32 
21.42 
28.50 
60.66 


17.73 
22.08 
27.12 
36.06 

74.82 


0.0337 
.0323 
.0323 
.0320 

.0288 


0.0269 
.0274 
.0266 
.0262 
.0233 


0.352 
.423 
.524 
.694 

1.358 


0.375 
.476 
.570 
.748 

1.416 


=0.80  X10-5     1.06  X10-6     1. 32X10-* 


Mol. 
Cone. 


D25°/4° 


Viscosity  and  Fluidity. 


7j35c 


Temperature 
Coefficients  (<f>). 


15-25° 


25-35c 


0.10 
Solv. 


1.1395 
1 . 1307 


0.04943 
.04409 


0.03682 
.03325 


0.02947 
.02655 


20.23 
22.68 


27.16 
30.08 


33.93 
37.66 


0.0343 
.0326 


0.0249 
.0252 


TABLE  46. — Sodium  Salicylate  in  Formamid. 


V 

Molecular 
Conductivity. 

Temperature  Coefficients  of 
Conductivity. 

Per  cent. 

Conductivity 
Units. 

15° 

25° 

35° 

15-25° 

25-35° 

15-25° 

25-35° 

4  

9.65 
11.74 
13.70 
14.49 
14.80 
17.10 
/ 

13.06 
15.51 
18.04 
19.01 
19.27 
22.13 
C=0.68X 

16.56 
19.79 
22.95 
24.12 
24.40 
27.26 
10~6     0. 

0.0353 
.0321 
.0317 
.0312 
.0300 
.0295 
83X10-5 

0.0267 
.0276 
.0272 
.0269 
.0266 
.0232 
1.06X10 

0.341 
.377 
.434 
.452 
.447 
.503 

-6 

0.350 
.428 
.491 
.511 
.513 
.513 

10  ... 
50 

200 

400 

1600 

Mol. 
Cone. 

Viscosity 

and  Fluidity. 

Temperature 
Coefficients  (?). 

Z>25°/4° 

7,15° 

i?25° 

i;350 

*>15° 

y>25° 

*>35° 

15-25° 

25-35° 

0.25 
0.10 
Solv. 

1.1417 
1.1345 
1.1306 

0.05374 
.04787 
.04379 

0.03988    0 
.03571 
.03317 

.03136 
.02859 
.02648 

18.61 
20.89 
22.84 

25.08 
28.00 
30.15 

31.89 
34.98 
37.76 

0.0348 
.0340 
.0320 

0.0272 
.0249 
.0252 

Conductivities  and  Viscosities  in  Formamid  and  in  Mixed  Solvents.       85 
TABLE  47.— Sodium  Benzene  Sulphonate  in  Formamid. 


V 

Molecular 
Conductivity. 

Temperature  Coefficients  of 
Conductivity. 

Per  cent. 

Conductivity 
Units. 

15° 

25° 

35° 

15-25° 

25-35° 

15-25° 

25-35° 

10 

12.05 
13.90 
14.52 
14.76 
16.40 

15.87 
18.23 
19.01 
19.04 
20.90 
K>0.8X 

20.21 
23.06 
24.00 
24.39 
26.82 
10~5     1.0 

0.0317 
.0301 
.0309 
.0290 
.0274 
5X10-5 

0.0273 
.0265 
.0262 
.0280 
.0283 
1.32X10- 

0.382 
.433 
.449 

.428 
.450 

6 

0.434 
.483 
.499 
.547 
.592 

50 

200 

400   
1600 

Mol. 
Cone. 

Viscosity 

and  Fluidity. 

Temperaturc 
Coefficients  (v>). 

£>25°/4° 

7715° 

i;250 

1735° 

V>15° 

*>25° 

*>35° 

15-25°       25-35° 

0.10 
Solv. 

1  .  1360 
1.1306 

0.04727 
.04379 

0.03554    0 
.03317 

.02836 
.02648 

21.17 

22.84 

28.14 
30.15 

35.26 
37.76 

0.0329        0.0253 
.0320          .0252 

TABLE  48. — Sodium  Succinate  in  Formamid. 


Temperature  Coefficients  of 

V 

Molecular 
Conductivity. 

Dissociation. 

Conductivity. 

Per  cent. 

Conductivity 
Units. 

15° 

25° 

35° 

15° 

25° 

35° 

15-25° 

25-35° 

15-25° 

25-35° 

10 

21.72 

28.71 

36. 

59 

62.2 

64.3 

66.6 

0.0321 

0.0274 

0.69S 

0.788 

50 

29.54 

38.82 

49. 

04 

84.4 

87.0 

89.2 

.0314 

.0263 

.928 

1.012 

200 

32.56 

42.67 

53. 

84 

90.3 

95.6 

97.9 

.0308 

.0252 

1.011 

1.117 

400 

33.20 

43.32 

54. 

24 

90.5 

97.1 

98.6 

.0304 

.0252 

1.012 

1.092 

1600 

34.88 

44.59 

54. 

95 

100.0 

100.0 

100.0 

.0298 

.0233 

.979 

1.036 

K 

=0.6X10-»    0.8  X10~*     1.06X10"5 

Mol. 

Viscosity  and  Fluidity. 

Temperature 
Coefficients  (<f>). 

Cone. 

D25°/4° 

7,15° 

T725° 

,35° 

V>15° 

*>25° 

*35° 

15-25° 

25-35° 

0.10 

1.1381 

0.05254 

0.03907    0 

.03110 

19.03 

25.60 

32.15 

0.0345 

0.0256 

Solv. 

1  .  1295 

.04402 

.03319 

.02678 

22.72 

30.13 

37.34 

.0326 

.0239 

Studies  on  Solution. 


TABLE  49. — Tetraethylammonium  Iodide. 

In  7    per  cent  formamid  and  25  per  cent  ethyl  alcohol. 
Specific  conductivity  25°.     Formamid,  14 XH)-6.     Ethyl  alcohol,  4.1  X10~7. 


V 

Molecular 
Conductivity. 

Temperature  Coefficients  of 
Conductivity. 

Per  cent. 

Conductivity 
Units. 

15° 

25° 

35° 

15-25° 

25-35° 

15-25° 

25-35° 

4 

13.31 
19.96 
23.38 
24.64 
24.75 
24.96 
24.82 
tf  =  1.0 

17.13 
25.70 
29.76 
31.44 
31.69 
31.95 
31.95 
XIO-5!.! 

21.14 
31.72 
36.86 
38.91 
39.15 
39.53 
39.24 
J5X10-* 

0.0287 
.0287 
.0274 
.0276 
.0280 
.0280 

0.0234 
.0234 
.0328 
.0237 
.0236 
.0237 

0.382 
.374 
.638 
.680 
.694 
.699 

0.401 
.602 
.710 
.747 
.746 
.758 

10                

50                 »  

100         

200  

400  

1600  

1.  57X10-* 

Mol. 
Cone. 

Viscosity  and  Fluidity. 

Temperature 
Coefficients  fa). 

Z>25°/4°       Tjl5°          1725° 

i;350 

^15° 

*>25° 

V>35° 

15-25° 

25-35° 

0.25 
0.10 
Solv. 

1.0436    0.03639    0.02763    0 
1.0330      .03469      .02661 
1.0260      .03389      .02577 

02228 
02132 
02066 

27.48 
28.83 
29.51 

36.19 
37.72 
38.80 

44.88 
46.90 
48.40 

0.0317 
.0308 
.0315 

0.0240 
.0243 
.0247 

In  50  per  cent  formamid  and  50  per  cent  ethyl  alcohol. 

> 

Molecular 
Conductivity. 

Temperature  Coefficients  of 
Conductivity. 

Per  cent. 

Conductivity 
Units. 

15° 

25° 

35° 

15-25° 

25-35° 

15-25° 

25-35° 

4 

18.80 
22.23 
27.24 
29.49 
29.96 
31.00 
X-l 

23.29 
27.92 
34.01 
36.71 
37.24 
38.64 

.01x10- 

28.59 
33.94 
41.30 
44.67 
45.26 
46.95 
'     1.24  X 

0.0239 
.0250 
.0248 
.0245 
.0245 
.0246 
10-6     1.4( 

0.0227 
.0219 
.0214 
.0215 
.0215 
.0215 

>xio-^ 

0.449 
.559 
.677 
.722 
.734 
.765 

0.530 
.613 
.729 
.796 
.802 
.831 

10  

50  ...........  

100 

200     .......      . 

400  . 

Mol. 
Cone. 

Viscosity 

and  Fluidity. 

Temperature 
Coefficients  (<f>). 

D25°/4°      1715°          1725° 

1735° 

¥>15° 

*>25° 

^35° 

15-25° 

25-35° 

0.25 
.10 
.02 
Solv. 

0.9570   0.02666   0.02086   C 
.9437      .02571      .02002 
.9369      .02494      .01953 
.9346      .02488      .01939 

.01707 
.01631 
.01597 
.01580 

37.51 
38.90 
40.10 

47.94 
49.95 
51.20 

58.58 
61.31 
62.62 

0.0278 
.0284 
.0277 
.0283 

0.0222 
.0227 
.0223 
.0227 

Conductivities  and  Viscosities  in  Formamid  and  in  Mixed  Solvents.       87 


TABLE  49. — Tetraethylammonium  Iodide — Continued. 
In  25  per  cent  formamid  and  75  per  cent  ethyl  alcohol. 


Molecular 
Conductivity. 


15°          25°          35 


Temperature  Coefficients  of 
Conductivity. 


Per  cent. 


15-25°      25-35 


Conductivity 
Units. 


15-25°    25-35° 


4 

10 

50 

100 

200 

400 

800 

1600 


Saturated  solution. 


22.28 
29.21 
32.43 
34.08 
36.04 
36.72 
38.13 


27.86      33.92 


35.56 
39.41 
.41.34 
43.79 
44.46 
46.08 


42.61 
47.17 
49.36 
52.29 
53.15 
54.90 


0.0219 
.0219 
.0215 
.0213 
.0215 
.0210 
.0209 


0.0208 
.0198 
.0194 
.0194 
.0194 
.0195 
.0191 


0.482 
.635 
.698 
.726 
.775 
.774 
.795 


0.560 
.705 
.776 
.802 
.850 
.869 
.882 


1.56  X10~6    1.80  X10-5     1.99  XIO"6 


Mol. 
Cone. 


Z)25°/4 


Viscosity  and  Fluidity. 


7J250          7735' 


Temperature 
Coefficients  (<p) 


15-25C 


25-35c 


0.10 
.02 

Solv. 


0.8663 

.8580 

0.8554 


0.01828 
.01795 
.01761 


0.01474 
.01438 
.01412 


0.01257 
.01197 
.01174 


54.70 
55.71 
56.79 


67.84 
69.54 
70.82 


80.84 
83.54 

85.18 


0.0240 
.0248 
.0247 


0.0192 
.0168 
.0203 


TABLE  50. — Rubidium  Iodide. 

In  75  per  cent  formamid  and  25  per  cent  ethyl  alcohol. 
Specific  conductivity  25°.     Formamid,  1.6X15~5.     Ethyl  alcohol,  4.1  X10~7. 


Molecular 
Conductivity. 


15°          25 


35C 


Temperature  Coefficients  of 
Conductivity. 


Per  cent. 


15-25°      25-35° 


Conductivity 
Units. 


15-25°    25-35° 


4 

10 

50 

100 

200 

400 

1600 


20.00 
22.30 
24.70 
25.69 
25.92 
26.25 
26.73 


25.71 
28.45 
31.45 
32.78 
33.04 
33.48 
34.12 


31.55 
35.15 
38.75 
40.50 
40.88 
41.50 
42.27 


0.0285 
.0275 
.0273 
.0275 
.0275 
.0275 
.0276 


0.0227 
.0235 
.0232 
.0235 
.0237 
.0239 
.0239 


0.571 
.615 
.675 
.709 
.712 
.723 
.739 


0.584 
.670 
.730 
.772 
.784 
.803 
.815 


0.75  X10~5    0.96  X10-6     1.21XKT6 


Mol. 
Cone. 


0.10 

.02 

Solv. 


Viscosity  and  Fluidity. 


Z>25°/4°       rj!5°  r;250 


1.0417 
1.0300 
1.0257 


0.03468 
.03394 
.03366 


0.02657 
.02598 
.02573 


7725° 


0.02147 
.02086 
.02070 


28.84 
29.46 
29.71 


37.64 
38.49 

38.87 


46.58 
47.94 
48.31 


Temperature 
Coefficients  (<p). 


15-25°        25-35° 


0.0297 
.0306 
.0308 


0.0245 
.0246 
.0243 


Studies  on  Solution. 


TABLE  50. — Rubidium  Iodide — Continued. 
In  50  per  cent  formamid  and  50  per  cent  ethyl  alcohol. 


Molecular 
Conductivity. 


15°          25 


Temperature  Coefficients  of 
Conductivity. 


Per  cent. 


15-25°      25-35° 


Conductivity 
Units. 


15-25° 


25-35° 


4  . 
10  . 
50  . 

100  . 

200  . 

400  . 

1600  . 


21.39 
24.59 
28.47 
29.50 
30.25 
30.90 
32.02 


26.83 
30.64 
35.41 
36.75 
37.69 
38.47 
39.77 
0.35  X 10' 


32.60 
37.12 
43.00 
44.58 
45.83 
46.71 
48.12 


0.0254 
.0246 
.0244 
.0245 
.0245 
.0244 
.0242 


0.0215 
.0211 
.0214 
.0213 
.0216 
.0214 
.0210 


0.544 
.605 
.694 
.725 
.744 
.757 
.775 


0.577 
.648 
.759 
.783 
.815 
.824 
.835 


0.70X10-5     0.8  X10~5 


Mol. 
Cone. 


Viscosity  and  Fluidity. 


D25°/4C 


Temperature 
Coefficients  (> 


15-25C 


25-35c 


0.25 
.10 

Solv. 


0.9763 
.9515 
.9345 


0.02790  0.02190 
.02572  .02031 
.02471  !  .01934 


0.01769 
.01647 
.01577 


35.84 
38.88 
40.47 


45 . 66 
49.24 
51.71 


56.53 
60.72 
63.41 


0.0274 
.0266 
.0278 


0.0238 
.0233 
.0226 


In  25  per  cent  formamid  and  75  per  cent  ethyl  alcohol. 


Molecular 
Conduct  ivity. 


15°          25 


35° 


Temperature  Coefficients  of 
Conductivity. 


Per  cent. 


15-25°      25-35 


Conductivity 
Units. 


15-25°    25-35° 


4 

10 

50 

100 

200 

400 

1600 


20.92 
24.75 
30.49 
32.80 
34.06 
35.13 
36.69 


25.27 
29.98 
37.06 
39.85 
41.44 
42.75 
44.54 


30.03 
35.61 
44.05 
47.40 
49.38 
51.02 
53.28 


0.0208 
.0211 
.0215 
.0215 
.0216 
.0216 
.0214 


0.0188 
.0187 
.0188 
.0189 
.0191 
.0193 
.0194 


0.436 
.523 
.627 
.705 
.738 
.762 
.785 


0.476 
.563 
.699 
.755 
.793 
.826 
.878 


K  =0.425  X10~5    0.515  X10~5    0.608  XIO"6 


Mol. 
Cone. 


Viscosity  and  Fluidity. 


7715° 


»j250 


1735° 


V?35C 


Temperature 
Coefficients  (<p). 


15-25°        25-35° 


0.26 
.10 
.02 

Solv. 


0.8984 
.8723 

.8588 
.8549 


0.01996 
.01898 
.01777 
.01756 


0.01580 
.01483 
.01433 
.01414 


0.01309 
.01229 
.01189 
.01178 


50.12 
52.69 
56.27 
56.95 


63.29 
67.43 
69.78 
70.72 


76.39 
81.37 
84.10 

84.89 


0.0263 
.0280 
.0240 
.0242 


0.0207 
.0207 
.0205 
.0200 


Conductivities  and  Viscosities  in  Formamid  and  in  Mixed  Solvents.       89 


TABLE  51.— Lithium  Nitrate. 

In  75  per  cent  formamid  and  25  per  cent  ethyl  alcohol. 
Specific  conductivity  25°.     Formamid,  1.62  XlO~5     Ethyl  alcohol,  4.1  X10~7. 


Molecular 
Conductivity. 


15C 


25° 


35° 


Temperature  Coefficients  of 
Conductivity. 


Per  cent. 


15-25°      25-35° 


Conductivity 
Units. 


15-25°    25-35° 


10 

50 

200 

400 

1600 


18.71 
21.43 
22.76 
22.83 
22.79 


23.70 

27.08 
28.83 
29.08 
29.04 


29.12 
33.30 
35.41 
33.81 


0.0266 
.0263 
.0269 
.0273 


0.0228 
.0229 
.0228 


0.499 
.565 
.607 
.625 


0.542 
.622 
.658 


1.09  X10~5     1.37  X10~5 


Mol. 
Cone. 


Viscosity  and  Fluidity. 


D25°/4< 


i;15c 


i»25e 


Temperature 
Coefficients  (y>) 


15-25C 


25-35c 


0.25 

.10 

Solv. 


1.0353 
1 . 0292 
1.0249 


0.03800 
.03522 
.03373 


0.02879 
.02711 
.02576 


0.02312 
.02169 
.02091 


26.32 
28.39 
29.65 


34.73 
36.89 
38.82 


43.25 
46.10 

47.87 


0.0320 
.0299 
.0309 


0.0245 
.0252 
.0232 


In  50  per  cent  formamid  and  50  per  cent  ethyl  alcohol. 


Molecular 
Conductivity. 


loc 


25C 


35C 


Temperature  Coefficients  of 
Conductivity. 


Per  cent. 


15-25°      25-35° 


Conductivity 
Units. 


15-25°    25-35° 


10. 
50. 

200. 

400. 

1600. 


20.95 
23.72 
25.87 
26.41 
27.74 


24.74 
29.57 
32.09 
33.04 
35.11 


29.92 
35.87 
39.03 
40.26 
43.35 


0.0180 
.0204 
.0240 
.0251 
.0265 


0.0209 
.0214 
.0216 
.0218 
.0234 


0.379 
.485 
.622 
.663 
.737 


0.518 
.630 
.694 
.722 
.824 


#=0.75X10-5    0.93  X10-5     1.21  XHT6 


Mol. 
Cone. 


Viscosity  and  Fluidity. 


D25°/4< 


7,15' 


r?25c 


Temperature 
Coefficients  (<f>). 


15-25°   25-35 


0.25 
.10 

Solv. 


0.9457 
.9392 
.9344 


0.02861 
.02623 
. 02472 


0.02219 
.02083 
.01932 


0.01809 
.01674 
.01575 


34.95 
38.12 
40.45 


45.07 
48.01 
51.76 


55.28 
59.74 
63.49 


0.0289 
.0259 
.0280 


0.0227 
.0244 
.0227 


90 


Studies  on  Solution. 


TABLE  51.— Lithium  Nitrate — Continued. 
In  25  per  cent  formamid  and  75  per  cent  ethyl  alcohol. 


Molecular 
Conductivity. 


loc 


25° 


35C 


Temperature  Coefficients  of 
Conductivity. 


Per  cent. 


15-25°      25-35° 


Conductivity 
Units. 


15-25°    25-35° 


10 

50 

200 

400 

1600 


19.61 
25.49 
28.57 
29.64 
30.63 


23.81 
30.85 
34.84 
36.23 
38.24 


28.12 
36.82 
41.53 
43.27 
46.53 


0.0214 
.0210 
.0219 
.0222 
.0248 


0.0181 
.0193 
.0192 
.0194 
.0217 


0.420 
.536 
.627 
.659 
.761 


0.431 
.597 
.669 
.704 
.829 


0.74  X10~5  0.94  X10~5 


Mol. 
Cone. 


Viscosity  and  Fluidity. 


D25°/4° 


r;35c 


Temperature 
Coefficients  (<p) 


15-25° 


25-35c 


0.25 
.10 

Solv. 


0.8674 
.8600 
.8547 


0.02123 
.01895 
.01755 


0.01680 
.01522 
.01411 


0.01397 
.01260 
.01172 


47.10 
52.77 
56.98 


59.52 
65.70 
70.87 


71.58 
79.37 
85.32 


0.0264 
.0245 
.0244 


0.0203 
.0208 
.0204 


TABLE  52. — Calcium  Nitrate. 

In  75  per  cent  form  amid  and  25  per  cent  ethyl  alcohol. 
Specific  conductivity  25°.     Formamid,  1.62  X10~6.     Ethyl  alcohol,  1.41  X10~7. 


Molecular 
Conductivity. 


15C 


25C 


35° 


Temperature  Coefficients  of 
Conductivity. 


Per  cent. 


15-25°      25-35° 


Conductivity 
Units. 


15-25°    25-35° 


10 

50 

100 

200 

400 

1600 


31.02 
41.57 
44.79 
46.43 
48.90 
49.36 
K 


39.41 
52.82 
56.99 
59.07 
61.92 
61.57 


48,39 
65.03 
70.15 
72.79 
76.56 
78.40 


0.0274 
.0270 
.0272 
.0272 
.0266 
.0269 


0.0227 
.0231 
.0231 
.0232 
.0236 
.0273 


0.839 
1.125 
1.220 
1.264 
1.302 
1.321 


0.898 
.221 
.316 
.372 
.464 
.683 


1.80  X10-6    2.40  X10-6    3.00  X10~5 


Mol. 
Cone. 


Viscosity  and  Fluidity. 


Z>25°/4C 


i;25e 


i?35° 


Temperature 
Coefficients  (<p). 


15-25°       25-35° 


0.10 

.01 

Solv. 


1.0362 
1.0278 
1.0250 


0.03738 
.03455 
.03372 


0.02834 
.02642 
.02591 


0.02278 
.02110 
.02078 


26.75 
28.94 
29.66 


35.28 
37.86 
38.60 


43.90 
47.39 
48.22 


0.0310 
.0308 
.0301 


0.0253 
.0252 
.0249 


Conductivities  and  Viscosities  in  Formamid  and  in  Mixed  Solvents.       91 


TABLE  52. — Calcium  Nitrate — Continued. 
In  50  per  cent  formamid  and  50  per  cent  ethyl  alcohol. 


10 

50 

100 

200 

400 

1600 


Molecular 
Conductivity. 


15C 


27.58 
41.14 
43.18 
49.54 
52.03 
54.62 
K 


25° 


34.30 
50.97 
53.30 
61.66 
65.14 
68.51 


Temperature  Coefficients  of 
Conductivity. 


Per  cent. 


15-25° 

0.0243 
.0238 
.0234 
.0244 
.0251 
.0254 


25-35c 


1.50X10-5     1.90X10~5 


0.0205 

.0209 

.0213 

.0208 

.0203 

.0189 
2.40  X10~5 


Conductivity 
Units. 


15-25C 


0.672 
.983 
1.012 
1.212 
1.311 
1.389 


25-35e 


0.706 
1.066 
1.130 
1.284 
1.327 
1.297 


Mol. 
Cone. 


Viscosity  and  Fluidity. 


D25°/4e 


,,15° 


Temperature 
Coefficients  (<p). 


15-25C 


25-35c 


0.10 

.02 

Solv. 


0.9463 
.9376 
.9342 


0.02774 
.02560 
.02475 


0.02158 
.01976 
.01934 


0.01755 
.01610 
.01567 


36.05 
39.06 
40.40 


46.34 
50.61 
51.71 


56.98 
62.11 
63.82 


0.0285 
.0296 
.0280 


0.0230 
.0227 
.0234 


In  25  per  cent  formamid  and  75  per  cent  ethyl  alcohol. 


10 

50 

100 

200 

400 

1600 


Molecular 
Conductivity. 


15C 


19.48 
32.03 
37.69 
43.17 
48.19 
55.88 


23.37 
38  2. 
45. 0^ 
51.78 
57.93 
67.36 


35° 


27.72 
45.07 
52.78 
60.70 
68.35 
79.66 


Temperature  Coefficients  of 
Conductivity. 


Per  cent. 


15-25C 


0.0199 
.0192 
.0196 
.0199 
.0202 
.0205 


25-35c 


0.0185 
.0177 
.0170 
.0172 
.0179 
.0182 


Conductivity 
Units. 


15-25C 


0.389 
.618 
.739 
.861 
.974 

1.148 


1.30  X10~5     1.54X10-3 


25-35° 


0.435 

.686 

.770 

.892 

1.042 

1.230 


DISCUSSION  OF  RESULTS. 

In  tables  30  to  35,  inclusive,  are  given  the  conductivity  and  viscosity 
data  for  the  ammonium,  sodium,  potassium,  calcium,  barium,  and 
strontium  nitrates  at  the  different  temperatures  studied.  The  con- 
ductance values  at  infinite  dilution  were  reached  at  dilutions  below 
M/600  for  all  except  barium  and  calcium  nitrates.  Beyond  this 
dilution  no  measurements  were  made,  since  in  most  cases  the  solvent 
correction  becomes  equal  to  or  greater  than  one-half  the  observed 
conductances. 


92 


Studies  on  Solution. 


In  table  53  a  comparison  is  made  of  the  conductances  and  disso- 
ciation of  these  nitrates  in  formamid  with  similar  results  in  water  as 
the  solvent.  While  the  two  sets  of  results  are  based  on  different 
schemes  of  dilution  (M/10  and  M/8),  the  two  concentrations  are 
sufficiently  close  together  to  permit  a  general  comparison.  From  the 
data  in  the  table  it  appears  that  the  molecular  conductivity  values  for 
these  nitrates  in  formamid  are  much  smaller  than  in  water,  although  the 
order  of  increasing  conductivity  is  the  same  in  both  solvents. 

The  greater  dissociating  power  of  formamid  as  compared  with  water 
is  also  shown  by  the  table.  It  is  further  illustrated  by  the  fact  that 
complete  dissociation  is  reached  by  these  salts  at  much  lower  dilution 
than  in  water.  For  example,  sodium  nitrate  is  completely  dissociated 
in  formamid  at  M/800,  while  in  water  this  is  not  reached  until  M/2048. 

TABLE  53. — Comparison  of  the  Conductivity  and  Dissociation  of  the  Alkali  and 
Alkaline  Earth  Nitrates  in  Formamid  and  in  Water  at  25°  C. 


Formamid. 

Water. 

Nitrate. 

Mio 

a 

M8 

a 

Lithium  .... 

21.88 

87.0 

84.7 

79.5 

Sodium  

23.32 

84.0 

96.6 

77.9 

Potassium.  . 

24.38 

80.0 

117.99 

79.5 

Rubidium.  . 

25.59 

90.0 

125.54 

Csesium  

25.76 

87.0 

127.56 

Ammonium  . 

28.00 

87.0 

120.65 

82.0 

Barium  

36.93 

63.0 

155.62 

61.1 

Strontium.  . 

39.24 

69.0 

164.34 

64.6 

Calcium  .... 

39.50 

68.0 

167.21 

64.8 

Lithium  nitrates  crystallize  with  water  of  crystallization,  while 
sodium,  potassium,  and  ammonium  nitrates  do  not.  According  to 
the  theory  of  Jones  and  others,  this  is  an  indication  that  the  lithium 
ion  is  more  solvated  in  solution  than  are  the  ions  of  sodium,  potassium, 
or  ammonium.  The  effect  of  such  solvation  is  that  lithium  ions  move 
more  slowly  than  those  of  the  other  alkali  ions,  and  consequently  the 
conductivities  are  much  smaller.  The  solvate  theory  is  a  plausible  ex- 
planation for  the  smaller  conductivity  values  of  lithium  salts,  regardless 
of  the  much  smaller  mass  and  atomic  volume  of  lithium  as  compared 
with  the  other  alkali  metals. 

The  conductivities  of  the  nitrates  of  barium,  strontium,  and  calcium 
in  formamid  are  analogous  in  every  respect  to  the  conductivity 
phenomena  of  these  salts  in  water — i.  e.,  they  show  evidence  for  the 
formation  of  complexes  with  the  solvent.  As  an  indication  of  this,  the 
temperature  coefficients  of  conductivity  expressed  in  conductivity 
units  are  higher  for  these  salts  than  for  the  alkali  nitrates,  which  have 


Conductivities  and  Viscosities  in  Formamid  and  in  Mixed  Solvents.       93 


little  or  no  solvating  power.  This  may  be  accounted  for  upon  the  basis 
of  a  decrease  in  the  complexity  of  the  solvate  with  rise  in  temperature, 
giving  greater  mobility  to  the  ions. 

The  viscosities  of  the  solutions  of  these  nitrates  in  formamid  increase 
in  numerical  value  as  we  pass  from  the  alkalis  to  the  alkaline  earths — 
i.  e.,  the  effect  of  the  anion  being  the  same,  the  viscosity  varies  with  the 
size  of  the  cation,  the  increase  in  viscosity  being  less  in  the  case  of  the 
salts  of  caesium,  rubidium,  and  ammonium  and  becoming  greater  as  we 
pass  through  those  of  potassium  and  sodium  to  calcium,  barium,  and 
strontium.  There  are  two  w^ays  of  viewing  this  phenomenon.  From 
the  standpoint  of  the  theory  of  Jones  and  Veazey,  the  smaller  increment 
in  the  viscosity  of  the  solvent  caused  by  the  salts  of  the  first  three 
alkali  metals  is  due  to  their  large  atomic  volume,  which  produces  a 
decrease  in  the  total  fractional  surfaces  of  the  particles  in  a  given 
volume  of  the  solution.  On  the  other  hand,  it  has  been  shown  that 
substances  with  the  largest  molecules  give  the  greatest  increase  in  the 
viscosity  of  the  medium  and  that  by  increasing  the  complexity  of  the 
solvent  the  viscosity  of  the  solution  becomes  greater.  From  this 
standpoint  it  would  appear  that  the  small  increment  in  the  viscosity  of 
formamid  caused  by  salts  of  caesium,  rubidium,  and  ammonium  is  due 
to  the  slight  solvation  of  their  cations,  while  the  greater  value  obtained 
for  the  other  alkalis  and  for  the  salts  of  the  alkaline  earths  is  due  to  the 
increase  in  the  complexity  of  the  solute  due  to  solvation,  the  resulting 
complex  being  larger  than  the  non-solvated  ions  of  the  alkali  metals. 
Previous  work  in  this  laboratory  has  supported  the  view  of  Jones  and 
Veazey,  but  the  work  in  mixed  solvents  containing  formamid  to  be  dis- 
cussed later  seems  to  favor  the  latter  hypothesis. 

TABLE  54. — Comparison  of  Conductivity  and  Dissociation  of  Formates  in 
Formamid  and  in  Water  at  25°  C. 


Formate. 

Formamid. 

Water.1 

M60 

a 

M32 

a 

Rubidium  .  . 
Lithium  .... 
Sodium.  .  .  . 
Ammonium  . 
Strontium  .  . 

16.97 
21.22 
22.64 
28.09 
41.54 

98.0 
89.4 
93.8 
92.9 
76  0 

138.4 

87.9 

Barium  

43.48 

84.0 

170.7 

76.5 

Carnegie  Inst.  Wash.  Pub.  Nos.  170  and  230. 

A  glance  at  table  54  will  show  that  these  salts  of  a  strong  organic 
acid  exhibit  similar  characteristics  in  formamid  to  the  nitrates— i.  e., 
they  are  more  strongly  dissociated  at  low  dilutions  than  in  water, 
although  the  actual  conductance  is  much  less.  The  temperature 


94 


Studies  on  Solution. 


coefficients  of  conductivity  expressed  in  conductivity  units  (see  tables 
36  to  41)  are  all  of  the  same  order  of  magnitude  for  the  alkalis,  but 
again  are  larger  in  the  case  of  the  alkaline  earths. 

Owing  to  the  limited  solubility  of  these  salts  in  formamid,  viscosity 
measurements  were  made  only  on  the  alkali  formates.  Rubidium 
and  ammonium  formates  increase  the  viscosity  of  the  solvent  to  a  less 
extent  than  do  sodium  and  lithium  formates;  this  behavior  being  analo- 
gous to  that  of  the  nitrates. 

TABLE  55. — Comparison  of  Conductivity  and  Dissociation  of  Sodium  Salts  of 
Organic  Acids  in  Formamid  and  in  Water  at  25°  C. 


Sodium  Salt. 

Formamid. 

Water.1 

M60 

a 

M32 

a 

m-brombenzoic  acid  
1,  3,  5  di-nitrobenzoic  acid  
m-aminobenzoic  acid  
Benzole  acid  
Salicylic  acid  
Benzene  sulphonic  acid  
Succinic  acid  

13.92 
13.95 
14.34 
15.03 
15.51 
15.87 
28  71 

76.0 

67.2 

65.9 
68.7 
68.3 
69.1 
81.7 

.... 

'Bull.  Imp.  Acad.  Sci.  St.  Petersburg  (1911).     Translation  in  German. 

Table  55  brings  out  very  clearly  that  the  conductance  capacity  of 
the  first  three  salts  is  approximately  equal,  and  the  same  is  true  of  the 
next  three.  All  of  the  monobasic  salts  have  very  nearly  the  same  con- 
ductance, while  the  dibasic  salt,  being  a  ternary  electrolyte,  has  about 
twice  their  conductance.  The  same  fact  is  brought  out  by  the  recent 
work  of  Lloyd  and  Pardee  in  their  data  for  conductivity  in  pure  alcohol. 
(See  Chapter  III.) 

The  conductivity  of  the  first  three  salts  in  the  table  showed  a  remark- 
able increase  in  dilute  solutions.  The  sodium  salts  of  these  organic 
acids  tend  to  increase  in  conductivity  upon  standing.  Apparently 
no  relation  is  brought  out  by  the  conductivity  values  in  regard  to  the 
constitution  of  the  organic  salts. 

An  attempt  was  made  to  measure  the  conductivity  of  benzoic  and 
salicylic  acids  in  formamid,  with  the  result  that  the  conductivity 
values  increased  at  the  rate  of  about  one  integer  an  hour.  Walden, 
however,  has  measured  the  conductivity  of  some  aliphatic  acids  and 
does  not  mention  this  phenomenon. 

The  viscosity  values  (see  tables  42  to  48)  for  solutions  of  these  organic 
salts  in  formamid  are  all  of  the  same  order  of  magnitude,  with  the  excep- 
tion of  sodium  succinate,  a  ternary  electrolyte,  which  gives  larger 
values.  As  in  the  case  of  the  conductivity  data,  there  is  little  evidence 
for  any  relation  between  viscosity  and  constitution,  although  the  viscos- 
ity appears  to  become  greater  with  increasing  complexity  of  the  acid. 


Conductivities  and  Viscosities  in  Formamid  and  in  Mixed  Solvents.       95 


Tables  49  to  52  show  the  molecular  conductivity  and  viscosity  of 
tetraethyl  ammonium  iodide,  rubidium  iodide,  lithium  nitrate,  and 
calcium  nitrate  in  binary  mixtures  containing  formamid  and  ethyl 
alcohol.  In  table  56  a  comparison  is  made  at  25°  between  the  con- 
ductivities in  these  mixtures  and  in  the  pure  solvents. 

TABLE  56. — Comparison  of  Molecular  Conductivity  in  Mixtures  of  Formamid 
and  Ethyl  Alcohol  at  25°. 


V 

HCONH2 
100  p.  ct. 

HCONHo 
75  p.  ct. 

HCONH2 
50  p.  ct. 

HCONH2 
25  p.  ct. 

C2H6OH 

100  p.  ct. 

10 

20.31 

25.70 

27.92 

27.86 

Insol. 

Tetraethyl  ammonium 

50 

22.69 

29.76 

34.01 

35.56 

iodide  

100 

23.79 

31.44 

36.71 

39.41 

I          200 

24.28 

31.69 

37.24 

41.34 

400 

31.95 

38.64 

43.79 

1  600 

31.95 

46.08 

^              A  j  \J\J\J 

10 

24.00 

28.45 

30.64 

29.98 

50 

25.27 

31.45 

35.41 

37.06 

Rubidium  iodide  

100 
)          200 

26.06 
26.41 

32.78 
33.04 

36.75 
37.69 

39.85 
41.44 

400 

33.48 

38.47 

42.73 

[     1,600 

34.12 

39.77 

44.54 

f           10 

20.58 

23.70 

24.74 

23.81 

'18.25 

50 

22.29 

27.07 

29.57 

30.85 

26.47 

Lithium  nitrate  

200 

23.66 

28.83 

32.09 

34.84 

32.31 

400 

23.63 

29.08 

33.04 

36.23 

34.12 

(     1,600 

29.04 

35.11 

38.24 

37.63 

10 

39.50 

39.41 

34.30 

23.37 

28.36 

50 

48.56 

52.82 

50.97 

38.21 

15.83 

Calcium  nitrate  

100 

52.98 

56.99 

53.30 

45.08 

19.56 

200 

54.89 

59.07 

61.66 

51.78 

23.81 

400 

55.90 

61.92 

65.14 

57.93 

25.19 

(     1,600 

58.54 

61.57 

68.51 

67.36 

35.40 

Carnegie  Inst.  Wash.  Pub.  No.  80,  84. 

One  of  the  most  important  facts  brought  out  in  this  table  is  that 
tetraethyl  ammonium  iodide,  rubidium  iodide,  and  lithium  nitrate 
show  an  increase  in  molecular  conductivity  up  to  a  concentration  of 
25  per  cent  formamid  and  75  per  cent  ethyl  alcohol  mixture.  Lithium 
nitrate  was  the  only  salt  of  these  three  whose  conductivity  values  in 
ethyl  alcohol  were  available,  and  as  these  values  are  about  of  the  same 
order  of  magnitude  as  those  in  pure  formamid,  it  appears  that  a  maxi- 
mum is  reached  in  conductivity.  This  relation  interpreted  in  terms  of 
previous  work  on  other  solvents  means  that  there  is  an  increase  either 
in  the  mobility  of  the  ions  or  in  the  dissociation  in  mixtures  with  75 
per  cent  ethyl  alcohol  and  25  per  cent  formamid,  or  both.  From  the 
viscosity  data  discussed  below  the  first  assumption  seems  to  be  the 
most  probable. 


96  Studies  on  Solution. 

The  viscosities  of  mixtures  of  formamid  with  ethyl  alcohol  as  well 
as  those  with  water  show  only  a  slight  deviation  from  the  normal 
values  for  mixtures,  being  always  somewhat  less  than  the  calculated, 
giving  rise  to  a  sagged  curve.  This  has  been  observed  by  Merry  and 
Turner,1  who  studied  the  viscosities  of  binary  mixtures  of  formamid 
with  methyl  and  ethyl  alcohols  and  with  water.  They  have  shown  this 
deviation  to  be  due  to  decrease  in  the  association  of  one  or  the  other 
components  or  of  both.  It  is  not  possible  to  account  for  this  phenom- 
enon by  the  theory  of  Jones  and  Veazey,  since  from  this  standpoint  a 
maximum  in  the  viscosity  curve  would  be  expected. 

The  conductivity  values  for  mixtures  containing  calcium  nitrate 
give  evidence  of  greater  variation  than  the  other  salts  in  analogous 
mixtures.  It  is  seen  in  table  56  that  the  maximum  in  the  values  for 
molecular  conductivity  does  not  occur  in  25  per  cent  formamid  and  75 
per  cent  ethyl  alcohol  mixtures  as  for  the  other  salts,  but  the  maxima 
appear  in  the  concentrated  formamid  mixture  and  in  the  concentrated 
solutions.  The  conductivity  is  greater  in  the  75  per  cent  to  25  per  cent 
mixture  than  in  the  formamid  itself. 

The  viscosity  of  the  solutions  of  the  four  salts  studied  in  these  mix- 
tures are  all  greater  than  those  of  the  solvents.  The  change  in  the 
association  of  the  two  components  is  evidently  so  slight  that  appar- 
ently the  size  of  these  molecular  aggregates  is  always  greater  than  that 
of  the  molecules  or  ions  of  the  solute.  Rubidium  and  tetraethyl 
ammonium  iodides  have  about  the  same  effect  on  the  viscosity  of  these 
mixtures.  Lithium  nitrate  and  calcium  nitrate  produce  a  much 
larger  increment  in  these  mixed  solvents  analogous  to  that  in  pure 
formamid.  The  actual  increase  in  the  viscosity  of  the  mixtures  for 
any  one  salt  becomes  greater  in  passing  from  the  mixture  containing 
the  larger  percentage  of  formamid  to  that  containing  the  larger  per- 
centage of  alcohol. 

A  few  measurements  were  made  on  the  viscosity  of  mixtures  of 
formamid  and  water,  the  results  confirming  those  obtained  by  Merry 
and  Turner2 — i.  e.,  the  viscosities  for  these  mixtures  show  a  much  greater 
deviation  from  the  law  of  mixtures  than  do  mixtures  of  formamid 
and  alcohol,  their  viscosities  being  much  less  than  those  calculated 
from  averages.  Caesium,  rubidium,  and  potassium  salts  lower  the 
viscosity  of  water,  but  increase  that  of  formamid.  Therefore  a  curve 
for  the  viscosities  of  solutions  of  these  salts  in  formamid- water  mixtures 
would  cross  that  of  the  solvent.  A  study  of  such  curves  would  yield 
some  interesting  results  and  probably  furnish  a  means  of  determining 
the  validity  of  the  hypothesis  of  Jones  and  Veazey,  which  has  been 
questioned  recently.3  It  is  hoped  that  we  may  be  able  to  take  up  this 
problem  at  some  future  time. 

Uourn.  Chem.  Soc.,  106,  748  (1914).  2Journ.  Chem.  Soc.,  106,  748  (1914). 

3C/.  Bramley:  The  Study  of  Binary  Mixtures.     Journ.  Chem.  Soc.,  109,  462  (1916). 


CHAPTER  III. 


A  NOTE  ON  THE  VISCOSITY  OF  CESIUM  SALTS  IN  GLYCEROL- 
WATER  MIXTURES. 


BY  P.  B.  DAVIS. 

The  study  of  the  viscosity  of  solution  in  glycerol  and  in  binary 
mixtures  containing  glycerol  was  begun  in  this  laboratory  by  Schmidt 
and  Jones1  a  number  of  years  ago.  They  noted  that  among  the  salts 
measured  potassium-iodide  solutions  lowered  the  viscosity  of  water  and 
mixture  of  glycerol  and  water  up  to  50  per  cent  glycerol,  although 
this  salt  increased  the  viscosity  of  pure  glycerol. 

Guy  and  Jones1  extended  this  work  in  connection  with  a  study 
of  the  conductivity  and  dissociation  of  electrolytes  in  glycerol  as  a 
solvent  and  noted  that  solutions  of  sodium  nitrate,  ammonium  bromide 
and  iodide,  and  rubidium  iodide  all  lowered  the  viscosity  of  pure 
glycerol  and  of  its  mixtures  with  water. 

These  results  led  Davis  and  Jones1  to  investigate  the  behavior  of 
glycerol  of  those  salts  known  to  decrease  the  viscosity  of  water.  They 
measured  the  viscosity  of  solution  of  certain  rubidium  and  ammonium 
salts  in  pure  glycerol  and  in  mixtures  of  glycerol  with  water  and  found 
that  the  salts  of  rubidium  and  ammonium  iodide  produced  a  phe- 
nomenal lowering  of  the  viscosity  of  glycerol,  the  molecular  conduc- 

TABLE  57. — Viscosity  and  Fluidity  of  Caesium  Chloride. 


Mol. 
Cone. 

7725° 

ij35° 

*>25° 

*>35° 

Temp. 
Coeff.  (*>). 
25-35° 

In  75  per  cent  glycerol 
with  water 

f  0.5 
.25 

0.3092 
.3184 

0.1945 
.1983 

3.234 
3.141 

5.141 
5.043 

0.590 
.606 

1      .10 

.3242 

.2016 

3.085 

4.960 

.608 

(  Solv. 

.3303 

.2207 

3.028 

4.531 

.496 

In  50  per  cent  glycerol 
with  water  

{0.50 
.25 

0.05974 
.06127 

0.04336 
.04477 

16.74 
16.32 

23.06 
22.34 

0.378 
.369 

.10 

.06189 

.  04478 

16.16 

22.33 

.388 

Solv. 

.06255 

.04536 

15.99 

22.05 

.379 

In  75  per  cent  glycerol 
with  water.   . 

0.50 
1      .25 

0.02019 
.02052 

0.01597 

49.53 
48.73 

62.62 

0.264 

.10 

.02063 

.01619 

48.47 

61.77 

.274 

Solv. 

.02070 

.01260 

48.31 

61.73 

.278 

Carnegie  Inst.  Wash.  Pub.  No.  180. 


97 


98 


Studies  on  Solution. 


tivity  of  these  salts  being  materially  increased  in  concentrated  solutions 
on  account  of  the  greater  fluidity  of  the  solution. 

In  order  to  complete  the  series  of  salts  lowering  the  viscosity  of  these 
solvents,  caesium  compounds  remained  to  be  measured.  A  supply  of 
caesium  carbonate  was  finally  obtained  and  converted  into  the  nitrate 
and  chloride.  The  viscosities  of  these  salts  have  already  been  measured 
in  water  and  in  mixtures  of  water  with  methyl  alcohol,  ethyl  alcohol, 
and  acetone.  Tables  57  and  58  give  similar  results  in  mixtures  of 
glycerol  and  water.  The  viscosities  were  measured  in  the  apparatus 
described  in  the  preceding  chapter  on  formamid. 

TABLE  58. — Viscosity  and  Fluidity  of  Ccesium  Nitrate. 


< 

Mol. 
Cone. 

r?25° 

7735° 

*>25° 

¥>35° 

Temp. 
Coeff.  (if). 
25-35° 

In  75  per  cent  glycerol 

f  0.25 

0.3089 

0.1933 

3.237 

5.173 

0.598 

with  water  

.10 

.3207 

.1990 

3.118 

5.025 

.612 

1  Solv. 

.3303 

.2207 

3.028 

4.531 

.496 

In  50  per  cent  glycerol 
with  water  

f  0.50 
j      .25 

0.05774 

.06043 

0.04223 
.04407 

17.32 
16.55 

23.68 
22.69 

0.367 
.371 

.10 

.  06149 

.  04443 

16.26 

22.51 

.384 

[  Solv. 

.06255 

.04536 

15.99 

22.05 

.379 

In  25  per  cent  glycerol 
with  water  

f  0.50 
.25 

0.01981 
.02031 

0.01566 
.01611 

50.48 
49  .  24 

63  .  86 
62.07 

0.265 
.261 

)      .10 

.02056 

.01615 

48.64 

61.92 

.273 

1  Solv. 

.02070 

.01615 

48.31 

61.92 

.282 

It  will  be  seen  from  tables  57  and  58  that  caesium  salts  decrease  the 
viscosities  of  glycerol-water  mixtures,  the  decrement  being  greater, 
however,  than  in  the  case  of  rubidium  salts.  It  should  also  be  noted 
that  when  salts  of  both  metals  increase  the  viscosity  of  a  solvent,  as  in 
the  case  of  certain  mixtures  of  water  with  acetone  and  the  alcohols, 
the  caesium  salts  produce  a  smaller  increment  than  rubidium  salts. 


CHAPTER  IV. 

A  STUDY  OF  THE  ELECTRICAL  CONDUCTANCE  OF  THE  SODIUM  SALTS 
OF  CERTAIN  ORGANIC  ACIDS  IN  ABSOLUTE  ETHYL  ALCOHOL  AT 
15°,  25°,  AND  35°. 


BY  H.  H.  LLOYD  AND  A.  M.  PARDEE. 


INTRODUCTION. 

In  the  Johns  Hopkins  laboratory,  for  some  years  past,  a  compre- 
hensive study  has  been  made  of  the  electrical  conductance  and  dissoci- 
ation of  various  organic  acids  in  aqueous  solution.1  This  work  was 
extended  to  absolute-alcohol  solutions  by  Wightman,  Wiesel,  and 
Jones,2  and  by  Lloyd,  Wiesel,  and  Jones.3  These  investigators  were 
unable  to  obtain,  or  even  to  approach,  experimentally  A0,  the  equiva- 
lent conductance  at  zero  concentration.  The  authors  have  therefore 
investigated  the  behavior  of  the  sodium  salts  of  the  organic  acids  in 
absolute  alcohol  in  order  to  obtain  first  the  A0  values  for  these  salts  and 
then,  by  substitution  in  the  Kohlrausch  equation,4  the  A0  values  for  the 
acids  themselves.  The  writers  are  interested  also  in  the  accumulation 
of  accurate  conductance  data,  as  well  as  in  such  questions  as  tempera- 
ture coefficients  of  conductance,  conductance  in  relation  to  chemical 
constitution,  limits  of  experimental  accuracy  in  working  with  dilute 
solutions  in  absolute  alcohol,  and  the  general  phenomenon  of  alco- 
holysis. 

HISTORICAL. 

The  measurement  of  the  electrical  conductance  of  the  sodium  salts 
of  organic  acids  in  absolute  alcohol  up  to  the  present  time  has  received 
but  scant  attention.  With  few  exceptions,  all  investigations  were 
incidental  in  nature  and  the  compounds  studied  were  chosen  simply 
as  types  of  organic  salts. 

Dutoit  and  Rappeport,5  in  a  study  of  the  limiting  conductances  of 
some  electrolytes  in  absolute  alcohol,  measured  sodium  acetate, 
among  other  salts,  evidently  taking  the  same  as  an  example  of  the  salts 
of  organic  acids.  They  subjected  their  results  to  some  rather  inter- 
esting deductions,  but  their  conductances  were  measured  at  18°,  mak- 

^arnegie  Inst.  Wash.  Pub.  No.  170,  part  n;  No.  210,  chap.  n. 

2Carnegie  Inst.  Wash.  Pub.  No.  210,  chap,  in;  Journ.  Amer.  Chem.  Soc.  36,  2243  (1914). 
'Carnegie  Inst.  Wash.  Pub.  No.  230,  chap.  VH;  Journ.  Amer.  Chem.  Soc.  38,  121  (1916). 
4W,  Ostv  aid :  Zeit.  physik.  Chem.,  2,  561  (1888) ;  3, 170  (1889) ;  Amer.  Chem.  Journ.  46, 66  (1914) . 
6Jour.  chem.  Phys.  6,  545  (1908). 

99 


100 


Studies  on  Solution. 


ing  exact  comparison  with  those  at  25°  an  impossibility.  They  inter- 
preted their  results  in  a  manner  similar  to  that  of  Goldschmidt,  and 
so  their  deductions  are  really  illustrated  in  the  latter's  communication. 

Dhar  and  Bhattacharyya1  carried  on  some  work  in  alcohol  with 
various  salts  and  studied  among  others  the  following  organic  deriva- 
tives: sodium  propionate,  sodium  benzoate,  and  sodium  salicylate. 
Then*  measurements  at  odd  concentrations  and  temperatures  render 
comparison  impossible. 

Heinrich  Goldschmidt,2  incidental  to  his  study  of  the  esterification 
of  organic  acids  in  absolute  alcohol,  found  it  necessary  to  measure  the 
conductances  at  25°  of  a  number  of  sodium  salts  of  these  acids.  The 
salts  were  made  by  neutralizing  the  alcoholic  solutions  of  the  acids 
with  an  alcoholic  solution  of  sodium  ethylate.  Goldschmidt  measured 
the  conductances  from  N/10  to  N/5120  concentrations,  and  the  values 
determined  for  five  different  salts  are  shown  in  tables  59  to  63.  These 
results  are  given  to  enable  us  to  discuss  them  and  the  deductions 
leading  from  them,  as  well  as  to  point  out  later  wherein  we  differ  from 
him  as  to  certain  conclusions.  These  salts  are  sodium  trichloroacet- 
tae,  dichloroacetate,  picrate,  salicylate,  and  sulphosalicylate.  There  is 
appended  to  each  table  his  calculation  of  A0  for  the  salt  at  specified 
dilutions. 


TABLE  59. — Sodium  Trichloroacetate. 


TABLE  60. — Sodium  Dichloroacetate. 


V 

Ai 

Ail 

10 

11.07 

20 

13.95 



40 

17.27 

17.33 

80 

20.99 

20.96 

160 

24.94 

25.12 

320 

28.83 

29.04 

640 

32.39 

32.50 

1280 

35.28 

35.29 

2560 

37.61 

37.48 

5120 

39.23 

38.92 

A*  1(320-1280)  =  46.10 

An    ,«,A_M«™=  46.20 

(1280-5120)  —  4 

Mean  A0 


V 

Ai 

An 

|Ain 

10 

Q  RS 

20 





12^64 

40 

ie!ii 

15.  95 

15.86 

80 

19.78 

19.59 

19.53 

160 

23.78 

23.65 

23.54 

320 

28.00 

27.70 

27.52 

640 

31.96 

31.51 

31.49 

1280 

35.66 

34.87 

34.96 

^2560 

38.42 

37.74 

38.02 

.5120 



40.71 

40.86 

A0    (320-  1280)  =  48  -54 

*                                    '  AQ    AO 

^0    (640-2560)  ~^'^ 
An    /oon     loom        Tr§  .UO 

I 

46 


°  (640-2560) 
A«  (1280-5120) 
A«  (320-1280) 
AO  (640-2560) 
A0  (1280-5120) 


=  48.36 

=  50.64 

=  47.36 

49.14 

50.90 


ii 


in 


Value  An  = , 


*Zeit.  anorg.  Chem.  82,  357  (1913).        2Zeit.  physik.  Chem.  89,  129  (1914) ;  91,  46  (1916). 


Electrical  Conductance  in  Absolute  Ethyl  Alcohol.  101 

TABLE  61. — Sodium  Salicylate.          TABLE  62. — Sodium  Sulphosalicylate. 


V 

A 

10 

9.57 

20 

12.21 

40 

15.27 

80 

18.78 

160 

22.67 

320 

26.58 

640 

30.14 

1280 

33.20 

2560 

35.48 

5120 

36.29 

V 

Ai 

An 

Mean. 

40 

13.50 

13.54 

13.5 

80 

16.72 

16.74 

16.7 

160 

20.21 

20.18 

20.2 

320 

23.76 

23.69 

23.7 

640 

27.06 

27.02 

27.0 

1280 

30.0 

30.03 

30.0 

2560 

32.22 

32.23 

32.2 

5120 

33.84 

34.12 

34.0 

AO  (320- 1280)  "fi*-8 
AO  (640-2560)  =  jfg- 
A0  (1280-5120)  =41.55 

Most  probable  value  =  44.5 


A0  (320-1280)  ~  2? 'I 
AO  (640-2560)  ~41. 1 
A0(  1280-5120)  =40.8 

An  =40.9 


TABLE  63. — Sodium  Picrate. 


V 

Ai 

An 

40 

18.04 

18.14 

80 

22.06 

22.11 

160 

26.34 

26.34 

320 

30.61 

30.64 

640 

34.59 

34.59 

1280 

37.94 

38.07 

2560 

40.43 

40.65 

5120 

42.03 

42.75 

L«  (320-1280) 
l°  (640-2560) 
L°(  1280-5120) 


=  50.421 
=  50.10  h 
48.99  J 

^0(320-1280)    =^*^  1 
A0  (640-2560)    =50.97       II 
A«(  1280-5120)  ~OU''Z  J 

Selected  value  =  51 


Goldschmidt  thought  that  it  was  evident,  after  carrying  his  dilutions 
to  5,120  liters,  that  A0  could  not  be  reached  by  ordinary  experimental 
methods.  He  attempted  to  calculate  A0  for  these  organic  salts  and 
expected  to  obtain  the  relative  velocity  of  the  organic  anion  from  the 
salt  and  introduce  the  same  into  the  equation 


To  determine  A0  for  the  organic  salt  he  made  use  of  the  Kohlrausch 
formula1 


in  which  A0  is  the  unknown  conductance  at  infinite  dilution,  A  the 
conductance  at  a  known  dilution  v,  and  a  an  unknown  constant.  Two 
equations  involving  the  use  of  different  A  values  are  equated,  the  A0 
being  the  same  in  both  cases,  and  the  expression  solved  for  the  value  a. 
Once  having  this,  it  is  a  simple  matter  to  solve  for  A0  in  one  of  the  two 

Ann.  26,  161  (1885). 


102 


Studies  on  Solution. 


TABLE  64.— KI  in  Abso- 
lute AlcoholConductances 
in  mhos  at  25°. 


original  equations.  By  reference  to  the  tables  quoted  above  we  can 
observe  how  such  values  are  derived.  It  is  to  be  noticed  that  alter- 
nate A  values  are  equated.  This  is  done  so  that  the  difference  may 
be  of  sufficient  degree  of  magnitude  and  that  any  inaccuracy  in  an 
individual  measurement  may  not  affect  two  successive  derivations. 

A  glance  at  the  tables  and  calculations  will  show  that  the  calculated 
values  of  A0  are  by  no  means  concordant.  The  higher  the  value  of  A 
used  in  the  equation,  the  lower  becomes  the  calculated  A0.  His  final 
conclusions  are  vague  and  inconclusive.  The  value  chosen  for  A0  must 
be  regarded  as  only  approximate;  it  was  usually  the  highest  possible. 

Goldschmidt  seems  to  have  overlooked  the  very  exact  and  admirable 
piece  of  work  done  on  the  subject  of  the  limiting  conductance  and 
degree  of  ionization  of  alcoholic  solutions  by  B.  B.  Turner1  in  the 
Johns  Hopkins  laboratory.     Turner  carried  his 
dilutions  to  far  greater  limits,  as  table  64  illus- 
trates.   We  have  repeated  this  work  and  have 
every  reason  to  believe  that  it  is  unquestioned 
and  is  remarkably  accurate,  especially  when  one 
considers  that  it  was  done  without  the  more  re- 
cent conductivity  apparatus  now  at  our  disposal. 

Turner  showed  that  up  to  5,000  liters  dilution 
it  is  easy  to  obtain  concordant  results;  but  the 
values  for  A0  as  calculated  according  to  the 
Kohlrausch  method  are  not  constant  for  these 
higher  dilutions.  Like  those  of  Goldschmidt, 
they  decrease  the  higher  the  values  of  A  used 
in  the  equation.  Turner  also  showed  that  plot- 
ting A  against  the  reciprocal  of  the  cube  root  of 
the  volume  does  not  give  a  straight  line  as  in 
aqueous  solutions  of  equal  dilutions,  but  rather 
a  smooth  curve  slightly  convex  towards  the  dilution  axis.  He  there- 
fore assumed  that  the  Kohlrausch  method  fails  to  answer  the  require- 
ments of  absolute  alcoholic  solutions.  Extrapolation  of  his  results  with 
the  formula  would  give  us  a  value  of  56  for  A0  instead  of  the  experi- 
mental value  of  48.5  obtained.  He  thought  that  accidental  introduc- 
tion of  water  into  his  solutions  might  affect  the  readings,  and  to  test 
this  he  added  as  much  as  0.2  to  0.3  per  cent  of  water  by  weight  to  his 
alcoholic  solutions,  with  a  variation  in  conductivity  of  only  0.01  X  10~6 
units,  showing  that  no  accidental  experimental  error  of  this  nature 
had  crept  hi. 

Furthermore,  Dutoit  and  Rappeport2  showed  identically  the  same 
phenomenon  with  a  number  of  inorganic  salts  in  work  to  which  reference 
has  already  been  made  (page  99).  This  work,  like  that  of  Turner, 


V 

A 

10 

22.2 

12 

23.0 

16 

24.1 

32 

27.5 

64 

31.1 

128 

35.0 

250 

38.2 

500 

41.4 

1000 

44.0 

5000 

47.8 

10000 

48.4 

20000 

48.5 

00 

48.5=*=0.5 

lAmer.  Chem.  Journ.  40,  558  (1908). 


2Journ.  chem.  Phys.  6,  545  (1908). 


Electrical  Conductance  in  Absolute  Ethyl  Alcohol.  103 

seems  to  have  escaped  the  notice  of  Goldschmidt,  as  he  does  not  mention 
either  piece  of  work  in  any  of  his  papers. 

In  other  words,  the  problem  as  undertaken  by  Goldschmidt  is  very 
incomplete  from  this  standpoint.  No  reason  can  be  given  why  he 
should  use  arbitrarily  chosen  limits  for  v  in  applying  the  Kohlrausch 
formula,  nor  is  it  shown  how  accurately  measured  conductances  up 
to  20,000  liters  dilution  can  be  reconciled  with  such  a  falling-off  in  the 
calculated  A0  for  the  salt. 

Whether  such  a  method  could  be  applied  or  not,  or  whether  another 
can  be  substituted  in  its  place,  is  a  question  of  very  great  importance. 
Furthermore,  Goldschmidt  based  his  conclusions  on  the  results  of 
only  six  or  seven  salts.  It  was  therefore  deemed  advisable  by  the 
present  writers,  in  the  first  place,  to  obtain  more  conductance  data  on  a 
larger  number  of  salts,  and,  in  the  second  place,  to  make  these  measure- 
ments at  several  temperatures  in  order  to  look  at  this  subject  in  a  broad 
way. 

EXPERIMENTAL. 
REAGENTS. 

The  alcohol  used  in  this  investigation  was  prepared  in  the  following 
manner:  Ordinary  95  per  cent  ethyl  alcohol  was  heated  for  several 
days  with  lime  in  a  copper  tank  with  a  glass  condenser  attached.  A 
minimum  of  refluxing  in  the  condenser  was  obtained  by  inserting  into 
the  tank  through  the  stopper  a  coil  of  3/16-inch  lead-pipe  containing 
running  water  and  serving  to  cause  condensation  immediately  below 
the  reflux  tube.  The  alcohol  was  distilled  off,  using  a  glass  still-head 
with  a  bulb  blown  in  it  and  containing  glass  wool  soaked  in  alcohol  in 
order  to  prevent  any  dusting  over  of  the  dry  calcium  hydroxide.  The 
middle  fraction  was  treated  in  the  same  manner  as  above  and  again 
fractionated.  This  process  was  continued  until  a  specific  gravity 
of  0.78507  was  obtained,  the  extreme  limits  of  variation  being  0.78505 
to  0.78510,  which,  according  to  Circular  No.  19  of  the  Bureau  of  Stand- 
ards, corresponds  to  a  purity  of  from  100  to  99.987  per  cent.  The 
specific  conductance  of  the  alcohol  varied  with  the  different  samples 
from  0.46  to  1.6X10"7  mhos.  Upon  the  final  distillation  the  alcohol 
was  collected  in  a  6-liter  alcohol-extracted  Jena  bottle  with  a  sealed 
stopper  carrying  a  siphon  for  drawing  off  the  liquid,  a  calcium  chloride- 
soda  lime  tube,  and  an  adapter  with  a  ground-glass  stopcock.  Alcohol 
prepared  and  stored  in  this  manner,  after  several  days  following  the 
distillation,  remained  practically  unchanged  as  to  its  conductance  for 
a  period  of  several  weeks.  It  was  found  that  our  discarded  alcoholic 
solutions  and  washings,  when  distilled  once  in  a  glass  vessel  with  a  few 
drops  of  concentrated  sulphuric  acid  before  the  final  lime  treatment, 
produced  a  very  superior  grade  of  "absolute"  alcohol,  being  generally 
better  than  that  obtained  from  fresh  supplies  of  the  95  per  cent  material. 


104  Studies  on  Solution. 

The  organic  salts  used  in  this  investigation  were  prepared  by  adding 
the  necessary  amount  of  sodium  ethylate  in  absolute  alcohol  to  the 
organic  acid  hi  alcoholic  solution,  as  advised  by  Goldschmidt  and  pre- 
viously mentioned  hi  the  historical  section  (page  100).  The  acids 
employed  were  taken  from  the  various  samples  purified  in  the  work  of 
Lloyd,  Wiesel,  and  Jones.  When  such  were  lacking  new  material  was 
obtained  from  well-known  firms  and  purified  in  the  following  man- 
ner: Whenever  possible  the  acid  was  recrystallized  from  hot  absolute- 
alcoholic  solution,  but  when  necessary  a  small  amount  of  water  was 
added.  In  every  case  the  fractionation  was  carried  out  several  times. 
The  halogen-substituted  aliphatic  acids  were  fractionally  crystallized 
from  hot  benzol,  placed  in  a  sulphuric-acid  desiccator,  and  the  final 
traces  of  benzol  were  removed  by  introducing  into  the  container  pieces 
of  paraffine,  which  acted  as  an  absorbent  for  the  solvent.  To  purify  the 
liquid  aliphatic  acids  we  resorted  to  both  fractional  crystallization  by 
means  of  a  refrigerant  and  repeated  distillations  under  reduced  pres- 
sure, hi  the  latter  case  collecting  the  various  fractions  in  a  specially 
constructed  receiver  for  small  quantities. 

The  ethylate  was  prepared  as  needed  in  the  following  manner,  as 
suggested  by  J.  H.  Shrader:1  A  special  grade  of  metallic  sodium,  free 
from  other  metals,  was  wiped  carefully  with  filter  paper,  the  approx- 
imate amount  was  pared  to  fresh  surfaces,  and  in  small  pieces  was 
put  first  in  a  good  grade  of  alcohol,  then  transferred  into  some  conduc- 
tivity alcohol  for  final  washing,  and  finally  dropped  into  a  measuring 
flask  of  the  best  alcohol,  so  that  upon  solution  it  could  be  made  up 
to  the  mark.  With  practice  it  was  possible  to  estimate  successfully 
the  amount  of  sodium  to  produce  a  nearly  N/10  solution.  This 
solution  was  standardized  and  used  within  an  hour  or  two  for  the  salt 
preparation.  It  was  found  necessary  to  use  the  ethylate  immediately, 
as  evidences  of  decomposition  giving  a  straw  color  to  the  solution 
appeared  within  24  hours  of  its  preparation,  and  even  sooner  in  the  case 
of  more  concentrated  solutions. 

This  ethylate  solution  was  immediately  standardized  by  means  of  an 
N/10  aqueous  solution  of  hydrochloric  acid.  This  latter  reagent  was 
prepared  by  the  method  of  Hulett  and  Bonner,2  lately  extended  by 
Hendrixson.3  As  a  check  on  this  solution  four  series  of  silver  chloride 
gravimetric  analyses  were  made  at  various  times  throughout  the  year, 
none  of  which  varied  more  than  0.1  per  cent. 

Phenolphthalein  served  as  the  indicator  for  the  various  titrations, 
special  precautions — noted  in  a  later  paragraph — being  used  to  prevent 
the  interference  of  carbon  dioxide  from  the  atmosphere.  As  a  final 
proof  of  the  correctness  of  our  choice  of  indicators,  the  ethylate  was 
standardized  with  hydrochloric  acid,  using  in  this  case  methyl  red  as 

*J.  H.  Shrader:  Dissertation,  Johns  Hopkins  University  14-16  (1913). 

2Journ.  Amer.  Chem.  Soc.  31,  390  (1909).        Mourn.  Amer.  Chem.  Soc.  37,  2352  (1915). 


Electrical  Conductance  in  Absolute  Ethyl  Alcohol.  105 

an  indicator,  and  it  showed  results  concordant  with  the  phenolphtha- 
lein  values  previously  obtained.  The  methyl  red  naturally  was  use- 
less in  the  titration  of  most  of  the  organic  acids,  so  its  use  was  aban- 
doned after  proving  the  value  of  the  phenolphthalein  procedure. 

In  order  to  dry  completely  our  various  pieces  of  apparatus,  acetone 
was  used,  as  suggested  by  Barnebey.1  The  acetone  was  dehydrated 
over  calcium  chloride  and  then  redistilled. 

APPARATUS. 

The  cylindrical  type  of  conductivity  cells  was  used  in  all  save  the  more 
concentrated  solutions,  where  the  ordinary  plate  type  was  adopted. 
The  reason  for  using  the  cylindrical  cell  lies  in  the  fact  that  the  organic 
salts  in  absolute  alcohol,  although  having  greater  conductance  than 
the  organic  acids,  are  nevertheless  of  sufficient  resistance  to  warrant 
such  a  procedure.  White2  and  Wightman3  have  described  the  method 
for  obtaining  the  constants  of  these  cells. 

Both  the  temperature  coefficients  of  expansion  of  alcohol  and  the 
temperature  coefficients  of  conductance  of  substances  in  it  as  a  solvent 
are  so  large  that  it  was  especially  necessary  to  maintain  the  solutions 
at  a  constant  temperature  to  within  0.01°.  The  thermometers  were  of 
the  differential  Beckmann  type  and  were  carefully  compared  with  a 
standard  Reichsanstalt  instrument  which  had  in  turn  been  calibrated 
at  the  Bureau  of  Standards.  The  combined  gas-regulator  and  thermo- 
regulator  was  devised  by  Davis  and  Hughes.4  The  improved  form  of 
constant-temperature  bath,  as  devised  by  Davis,5  was  used  in  our 
investigation.  These  baths  are  capable  of  even  finer  temperature 
adjustment  than  that  stated  above  as  employed  in  our  work. 

The  resistance-box  used  throughout  this  work  was  calibrated  at  the 
Bureau  of  Standards.  The  improved  Kohlrausch  slide-wire  bridge 
was  employed,  by  means  of  which  it  was  possible  to  read  distances  on 
the  slide  wire  corresponding  to  tenths  of  a  millimeter  (the  total  length 
of  the  wire  being  5  meters).  Special  precautions  were  taken  to  remove 
all  external  resistance  in  the  circuit.  No.  10  B.  &  S.  insulated  copper 
wire  was  used,  and  all  leads  coming  to  the  bridge  were  dipped  into  a 
mercury-contact  rocking  commutator. 

In  the  volumetric  work  Jena  flasks  were  employed  (50,  100,  200, 
250,  500,  1,000  c.c.)  which  had  been  previously  calibrated  in  this  labora- 
tory and  recalibrated  by  ourselves,  using  weight  methods.  Reichsan- 
stalt double-mark  pipettes  were  recalibrated  before  use.  In  filling 
and  draining  the  pipette  the  following  device  was  suggested  by  Dr. 
Davis.  It  consisted  of  a  right-angled  T-tube  with  a  glass  stopcock  on 
the  base  of  the  T,  the  pipette  being  attached  by  rubber  to  one  end  of 

1  Journ.  Amer.  Chem.  Soc.  37,  1835  (1915).        4Zeit.  physik.  Chem.  85,  519  (1913). 

'Amer.  Chem.  Journ.  42,  527  (1909).  'Carnegie  Inst.  Wash.  Pub.  No.  210,  21  (1914). 

3Amer.  Chem.  Journ.  44,  64  (1911). 


106  Studies  on  Solution. 

the  cross-piece,  held  vertically  with  the  regulating  finger  on  the  opposite 
end  of  the  cross-piece.  The  control  finger  is  maintained  throughout  the 
operation  at  this  opening  and  the  danger  of  contamination  by  suction 
is  removed.  A  tube  filled  with  a  mixture  of  calcium  chloride  and 
soda  lime  is  inserted  in  the  rubber  tube  leading  from  the  glass  stop- 
cock on  the  base  of  the  T  to  the  mouth,  for  obvious  reasons.  The 
50  c.c.  burettes  adopted  were  calibrated  at  2  c.c.  intervals  by  weight. 

In  order  to  titrate  with  phenolphthalein  in  an  atmosphere  free 
from  carbon  dioxide  the  following  apparatus  was  constructed,  partially 
as  suggested  by  Hendrixson  i1  A  carboy  was  connected  to  an  ordinary 
tire  pump  and  served  as  a  gas  reservoir.  The  air  was  led  through 
three  wash  bottles,  the  first  containing  concentrated  potassium  hydrox- 
ide solution,  the  second  a  more  dilute  solution,  and  the  third  pure 
water.  The  titration  was  effected  in  an  Erlenmeyer  flask  closed  with 
a  rubber  stopper,  which  in  turn  was  fitted  loosely  around  the  burette 
tip,  serving  in  this  way  as  a  vent  for  the  stream  of  air  passed  slowly 
through  the  solution. 

The  difficulty  in  desiccating  our  acids  when  once  purified  was 
solved  by  means  of  a  vacuum  drying-oven  designed  by  Dr.  Davis  and 
constructed  with  the  help  of  the  authors  (see  Chapter  II).  In  this 
apparatus  the  lamp  heating-unit  maintained  a  temperature  of  65° 
and  an  ordinary  suction-pump  kept  a  reduced  pressure  of  70  to  80  mm., 
so  it  is  easily  seen  that  with  the  added  help  of  a  strong  dehydrating 
agent,  such  as  sulphuric  acid  or  phosphorus  pentoxide,  all  traces  of  the 
crystallizing  solvent  could  be  removed,  since  water  boils  at  about  47° 
at  this  pressure.  In  proof  of  this  practically  all  the  organic  acids 
titrated  theoretically. 

PROCEDURE. 

The  sodium  e  thy  late  was  standardized  by  titration  with  N/10 
HC1  in  a  carbon-dioxide-free  atmosphere,  as  described  previously. 
When  the  ethylate  was  standardized,  the  organic  acid  from  which 
the  salt  was  to  be  made  was  weighed  out  in  quantity  sufficient  to  give 
100  c.c.  N/10  salt  solution  and  this  weight  was  confirmed  by  titration, 
which  showed  a  very  general  concordance,  giving  added  proof  of  the 
purity  of  the  acids.  In  dealing  with  very  deliquescent  substances,  as 
trichloracetic  acid  for  example,  we  weighed  by  difference,  making  ap- 
proximate standard  solutions  rather  than  exactly  N/10  strengths;  but 
even  in  this  case  we  obtained  confirmation  of  our  work.  The  non- 
deliquescent,  crystalline  acids  were  weighed  on  a  watch  crystal,  the 
deliquescent  ones  in  glass-stoppered  weighing  bottles;  but  in  both  cases 
the  acids  were  washed  through  a  funnel  into  the  100  c.c.  measuring 
flasks  with  conductivity  alcohol  and  made  up  to  mark  at  25°.  Several 

Uourn.  Amer.  Chem.  Soc.  37,  2352  (1915). 


Electrical  Conductance  in  Absolute  Ethyl  Alcohol. 


107 


salts  of  N/50  dilution  were  made  up  in  this  same  manner  at  the  begin- 
ning of  our  work,  but  this  dilution  was  omitted  later  as  unnecessary. 
Let  us  notice  a  few  of  the  necessary  steps  in  the  titrations.  All 
such  were  made  in  70  c.c.  solution  (50  c.c.  water,  10  c.c.  acid,  and 
approximately  10  c.c.  ethylate).  The  carbon-dioxide-free  air  was 
allowed  to  bubble  through  the  solution  for  2  minutes  before  titration. 
It  was  found  that  the  presence  of  some  alcohol  retarded  the  end-point 
and  a  number  of  titrations  were  made  throughout  the  year  to  enable 
us  to  correct  for  this.  We  found  as  a  result  of  our  work : 

70  c.c.  water  and  0  c.c.  alcohol  required  0.03  c.c.  to  produce  color. 
60  c.c.  water  and  10  c.c.  alcohol  required  0.04  c.c. 
50  c.c.  water  and  20  c.c.  alcohol  required  0.05  c.c. 

Therefore  it  was  necessary  to  apply  this  correction,  as  our  accuracy 
in  titration  was  made  to  check  to  0.02  c.c. 

After  calculating  the  amounts  necessary,  100  c.c.  N/100  salt  solution 
in  absolute  alcohol  at  25°  was  prepared,  placed  in  a  150  c.c.  glass- 
stoppered  Erlenmeyer  flask,  and  sealed  with  rubber  cement  until  the 
conductances  were  to  be  determined.  It  was  possible  to  make  up 
three  or  four  different  mother  solutions  of  various  organic  salts  in  one 
day,  another  day  being  devoted  to  the  dilution  down  to  weaker  con- 
centrations, measurement  of  the  conductances,  and  calculation  of  results 
for  each  salt.  These  last  three  operations  on  a  single  salt  at  various 
dilutions  we  have  designated  as  a  "run." 

It  is  deemed  advisable  at  this  point  to  introduce  an  example  of  the 
calculations  upon  which  a  single  salt  was  prepared  as  described  above : 

Acid  orthonitrobenzoic,  C?H6O4N.         Strength  of  standard  HC1,  0.10027. 


I.  Standardization  of  the  Ethylate. 
10.005  c.c.  HC1  used  in  each  titration. 

Ethylate  burette. 


II.  Standardization  of  the  OrganicAcid. 
10.005  c.c.  acid  used  in  each  titration. 

Ethylate  burette. 


Readings. 

Corrected. 

Difference. 

c.c. 

c.c. 

c.c. 

2.77 

2.76 

10.84 

10.83 

8.07 

10.85 

10.84 

.... 

18.91 

18.92 

8.08 

18.92 

18.93 

26.99 

27.02 

8.09 

Readings. 

Corrected. 

Difference. 

c.c. 

c.c. 

c.c. 

1.98 

1.98 

10.03 

10.02 

8.04 

10.03 

10.02 

18.05 

18.07 

8.05 

18.05 

18.07 

26.08 

26.11 

8.04 

Mean  8.08  less  0.04  correction  =  8. 04 

c.c.  ethylate. 

10.005  :8.04  :  :  x  :  0.10027 
a:  =  0.1248   normality  of  the  ethylate. 
To  make  100  c.c.  N/100  salt  solution 

requires  8.015  c.c. 


Mean  8.04  less  0.04  correction  =  8.00 

c.c.  ethylate. 

8.04  :  8.00  :  :  0.10027  :  x 
x  =  0.09977  normality  of  organic  acid. 
To  make  100  c.c.  N/100  salt  solution 

requires    10.02    c.c.    plus  0.01  c.c.; 

excess  equals  10.03  c.c. 


108 


Studies  on  Solution. 


It  should  be  mentioned  that  this  work  was  carried  on  in  a  rather 
small  room  with  one  window  and  one  door  at  opposite  ends  of  the 
room,  so  that  with  care  it  was  possible  to  keep  the  room  temperature  at 
25°  with  less  than  0.3°  variation.  Thus  it  was  possible  to  measure 
out  the  solutions  in  burettes  and  pipettes,  provided  that  such  were  not 
handled  unnecessarily  to  cause  heating  and  were  always  kept  dry  to 
prevent  cooling  in  evaporation.  All  burettes  and  pipettes  were  con- 
nected with  a  tube  filled  with  a  mixture  of  calcium  chloride  and 
soda  lime  to  prevent  contamination  from  moisture  and  carbon 
dioxide. 

In  handling  the  "run"  the  N/100  solution  of  one  of  the  salts  served 
as  a  basis  for  the  preparation  of  all  the  more  dilute  solutions.  The 
following  scheme  represents  the  method  by  which  these  solutions  were 
prepared  : 


N/,oo 


ZO^cto 
lOOCejsoln 

"Aoo 


iQcclto 
iOCcc|soM 

%ooo 


AQC.C   tO 

lOOcc  soln. 


20c.c   to 
iOOcc|so! 

r.oooo 


lOcc 
IOOc.c 


.lto 
Jsol 


After  a  number  of  experiments  it  was  deemed  inadvisable  to  wash 
the  measuring  flasks  with  water;  they  were  therefore  rinsed  with  a 
good  grade  of  alcohol  and  then  three  tunes  with  conductivity  alcohol. 
The  cells  were  filled  with  conductivity  water  until  several  hours  before 
use.  They  were  then  rinsed  three  times  with  good  alcohol.  Each 
cell  was  finally  washed  three  tunes  with  the  solution  of  the  particular 
dilution  to  be  "run"  in  that  cell  before  filling.  These  cells,  together 
with  one  containing  the  conductivity  alcohol,  were  then  introduced 
into  the  15°  bath,  gently  agitated  twice  within  an  hour's  time  to 
insure  absence  of  bubbles  as  well  as  to  hasten  diffusion,  and  then  read. 
They  were  placed  successively  in  the  25°  and  35°  baths,  allowing 
for  the  same  time  and  procedure  as  in  the  15°  bath. 

It  will  be  remembered  that  the  solutions  were  made  up  at  25°  and 
that  the  molecular  conductances  were  measured  at  15°,  25°,  and  35°. 
Alcohol  has  such  an  appreciable  temperature  coefficient  of  expansion 
that  it  was  necessary  to  correct  for  the  contraction  and  expansion  at 
the  other  temperatures.  One  liter  of  alcohol  at  25°  expands  to  1.01114 
liters  at  35°  and  contracts  to  0.98923  liter  at  15°.  Therefore,  to  obtain 
the  molecular  conductance  at  35°,  one  must  multiply  the  specific  con- 
ductance at  that  temperature  by  the  product  of  the  molecular  volume 
and  the  factor  1 .01 1 14.  Likewise,  to  obtain  the  molecular  conductance 
at  15°,  the  specific  conductance  at  that  temperature  must  be  multiplied 
by  the  product  of  the  molecular  volume  and  the  factor  0.98923. 


Electrical  Conductance  in  Absolute  Ethyl  Alcohol. 


109 


MEASUREMENTS. 
EXPLANATION  OF  TABLES. 

In  the  following  tables  V  signifies  the  volume  at  which  a  solution 
was  made  up,  A  the  molecular  conductance  of  that  solution  at  the  vari- 
ous temperatures.  The  method  of  calculating  A  is  thoroughly  familiar. 
Corrections  were  applied  as  described,  allowing  for  the  contraction  and 
expansion  of  the  solutions.  (The  solutions  were  so  dilute  that  their 
volume  changes  with  variation  in  temperature  were  assumed  to  be 
the  same  as  that  of  pure  alcohol.)  The  values  of  A  25°,  therefore,  rep- 
resent the  molecular  conductance  of  a  solution  of  volume  V  at  25°. 
The  values  of  A  15°  and  A  35°,  however,  represent  the  molecular  con- 
ductance of  a  solution  of  volume  0.98923  V  at  15°  and  1.01114  V  at  35°. 
Only  the  one  value  V  is  given  in  the  tables  to  save  space.  All  conduct- 
ances are  expressed  in  reciprocal  ohms. 

Concerning  the  calculation  of  the  temperature  coefficients  of  con- 
ductance, we  have  adopted  this  expression: 


where  At'  and  At  represent  the  molecular  conductivities  of  the  same 
solution  at  t'°  and  f  (tf>t),  and  T  the  temperature  coefficient  of  con- 
ductance. To  find  the  percentage  coefficient  of  conductance  we  have 
used  the  formula 

T 
' 


where  A  is  the  percentage  coefficient  and  At  the  conductivity  at  the 
lower  temperature.  At  first  the  values  of  At  and  At'  at  15°  and  35° 
were  corrected  for  the  difference  in  volume  between  0.98923  V  and  F, 
and  1.01114  V  and  F,  respectively.  This  was  done  in  order  that  com- 
parison might  be  made  between  solutions  of  the  same  volume.  Later 
this  correction  was  omitted  because  of  its  small  value. 


TABLE  65. — Sodium  Formate. 


V 

A25° 

A35° 

A25-350 

100 

20.09 

22.70 

1.30 

250 

25.03 

28.53 

1.40 

500 

28.48 

33.25 

1.67 

1,000 

32.62 

38.13 

.69 

2,000 

35.34 

41.88 

.85 

5,000 

37.75 

44.67 

.83 

10,000 

39.03 

46.35 

.88 

20,000 

39.76 

47.24 

.88 

TABLE  66. — Sodium  Acetate. 


V 

A25° 

A35° 

A25-350 

100 

17.20 

19.10 

1.10 

250 

22.20 

25.08 

1.30 

500 

26.07 

29.76 

1.42 

1,000 

29.99 

34.67 

.56 

2,000 

32.80 

38.54 

.75 

5,000 

35.42 

41.62 

.75 

10,000 

36.36 

42.84 

.78 

20,000 

36.79 

42.95 

.67 

110  Studies  on  Solution. 

TABLE  67. — Sodium  Chloroacetaie.  TABLE  68.— Sodium  Dichloroacetate. 


V 

A15° 

A25° 

A35° 

415-25° 

A25-350 

50 

12.92 

14.66 

16.40 

.35 

.19 

100 

16.15 

18.45 

20.74 

.42 

.24 

250 

20.52 

23.76 

26.92 

.58 

.33 

500 

23.76 

27.79 

32.04 

.70 

.53 

1,000 

26.51 

31.34 

36.56 

.82 

.67 

2,500 

29.19 

34.79 

41.00 

1.92 

.81 

5,000 

30.73 

36.81 

43.83 

1.98 

.91 

10,000 

31.53 

37.84 

45.02 

2.00 

1.90 

TABLE  69.— Sodium  Tnchloroacetate. 


V 

A15° 

A25° 

A35° 

A15-250 

A25-350 

100 

19.03 

22.05 

25.13 

1.59 

.40 

250 

23.26 

27.24 

31.36 

1.71 

.51 

500 

26.18 

30.94 

36.10 

1.82 

.67 

1,000 

28.80 

34.31 

40.31 

1.91 

.75 

2,000 

30.36 

36.40 

43.04 

1.99 

.82 

5,000 

32.24 

38.79 

46.12 

2.03 

.89 

10,000 

33.02 

39.84 

47.39 

2.07 

.90 

20,000 

33.71 

40.54 

48.39 

2.03 

.94 

TABLE  71. — Sodium  Propionate. 


V 

A15° 

A25° 

A35° 

A  15-25° 

A25-350 

100 

14.68 

16.50 

18.18 

1.24 

.02 

250 

18.80 

21.41 

23.95 

1.39 

.19 

500 

22.16 

25.71 

28.95 

1.60 

.29 

1,000 

25.13 

29.38 

33.85 

1.68 

.52 

2,000 

27.35 

32.28 

37.66 

1.80 

.67 

5,000 

29.26 

34.73 

40.64 

1.87 

.70 

10,000 

30.27 

36.11 

42.52 

1.93 

.77 

20,000 

30.52 

36  .  23 

42.41 

1.87 

.71 

TABLE  73. — Sodium  Butyrate. 


V 

A15° 

A25° 

A'iS0 

A  15  -25° 

A25-350 

100 

14  .  39 

16.16 

17.82 

1.23 

.03 

250 

18.50 

21.03 

23  .  49 

1.37 

.17 

500 

21.79 

24.97 

28.36 

1.46 

.  36 

1,000 

24.74 

28.89 

33.30 

.68 

.53 

2,000 

26.93 

31.80 

37.07 

.81 

.66 

5,000 

28.95 

34.29 

40.16 

.84 

.82 

10,000 

2Q.85 

35  .  67 

42.06 

.95 

.79 

20,000 

30.27 

35  .  98 

42.41 

.89 

.79 

V 

A15° 

A25° 

A35° 

A15-250 

A25-350 

100 

18.12 

20.84 

23.67 

.50 

1.36 

250 

22.38 

26.06 

29.91 

.64 

1.48 

500 

25.55 

30.00 

34.92 

.74 

1.64 

1,000 

28.36 

33.61 

39.40 

.85 

1.72 

2,000 

30.30 

36.12 

42.79 

.92 

1.85 

5,000 

32.16 

38.62 

46.01 

2.01 

1.91 

10,000 

33.08 

39.77 



2.02 

20,000 

33.97 

40.67 

48.71 

1.97 

1.98 

TABLE  70. — Sodium  PhenylacetaU . 


F 

A15° 

A25° 

A35° 

A15-250 

A25-350 

50 

11.14 

12.44 

13.60 

.17 

0.93 

100 

13.86 

15.58 

17.16 

.24 

1.01 

250 

17.96 

20.51 

22.91 

.42 

1.09 

500 

21.03 

24.31 

27.58 

.56 

1.35 

1,000 

24.09 

28.23 

32.36 

.72 

1.46 

2,500 

26.68 

31.60 

36.82 

.84 

1.65 

5,000 

28.06 

33.46 

39.31 

.92 

1.75 

10,000 

28.40 

34.06 

40.25 

1.99 

1.82 

TABLE  72. — Sodium  B-iodopropion"t< . 


V 

A15° 

A25° 

A35° 

A15-250 

A25-350 

50 

15.25 

17.67 

21.25 

1.59    2.03 

100 

18.54 

21.67 

26.48 

1.69 

2  22 

250 

22.59 

26.70 

33.27 

1.82 

2.46 

500 

25.51 

30.47 

38.13 

1.94 

2.51 

1,000 

27.91 

33  .  55 

42.09 

2.02 

2.55 

2,500 

30.18 

36  .  45 

45  .  50 

2.08 

2.48 

5,000 

31.39 

37.91 

47.39 

2.07 

2.50 

10,000 

31.93 

38  .  69 

48.06 

2.12 

2.43 

TABLE  74. — Sodium  Oxyixobulymlt 


F 

A15° 

A25° 

A35° 

A  15-25° 

A25-350 

50 

12.28 

14.21 

16.13 

.57 

1.35 

100 

15.39 

17.87 

20.32 

.61 

1.37 

250 

19.73 

23.07 

26.51 

.69 

1.49 

500 

22.74 

26.81 

31.11 

.79 

1.60 

1,000 

25.71 

30  .  52 

35  .  76 

.87 

1.72 

2,500 

28.07 

33.46 

39.52 

.92 

1.81 

5,000 

29.34 

35.07 

41.74 

.95 

1.90 

10,000 

30.23 

36.05 

42.97 

.93 

1.92 

Electrical  Conductance  in  Absolute  Ethyl  Alcohol.  Ill 

TABLE  75. — Sodium  Benzoate.  TABLE  76. — Sodium  Orthoamidobenzoate. 


V 

A15° 

A25° 

A35° 

A  15-25° 

A25-350 

100 

250 

18.94 

21.66 

24.29 

.45 

1.21 

500 

22.11 

25  .  66 

29.21 

.61 

1.38 

1,000 

25  .  03 

29  .  40 

33.93 

.75 

1.54 

2,000 

27.00 

31.99 

37.39 

.85 

1.69 

5,000 

29.18 

34.78 

40.83 

.92 

1.74 

10,000 

30.01 

35.80 

42.20 

.92 

1.82 

20,000 

30.41 

36.18 

42.64 

.90 

1.79 

TABLE  77. — Sodium  p-amidobenzoate. 


V 

A15° 

A25° 

A35° 

A15-250 

A25-350 

100 

12.26 

13.64 

14.92 

.13 

0.94 

250 

16.30 

18.50 

20.34 

.35 

0.99 

500 

1,000 

22.54 

26.13 

29.81 

.59 

1.41 

2,000 

24.87 

29.20 

33.80 

.74 

1.58 

5,000 

27.37 

32.37 

37.52 

.79 

1.63  1 

10,000 

28.33 

(33.21) 

(39.58) 

(1.72) 

(1.92) 

20,000 

28.92 

34.16 

(40.01) 

(1-81) 

(1.71) 

TABLE  79. — Sodium  p-brombenzoate. 


F 

A15° 

A25° 

A35° 

A15-250 

A25-350 

100 

15.71 

17.94 

20.11 

.42 

.21 

250 

19.78 

22.83 

26.00 

.54 

.39 

500 

22.84 

26.76 

30.89 

.72 

.51 

1,000 

25.37 

30.02 

34.94 

.83 

1.64 

2,000 

27.19 

32.46 

38.15 

.94 

.75 

5,000 

28.62 

34.31 

40.59 

.99 

1.84 

10,000 

29.41 

(35.09) 

42.05 

20,000 

29.84 

35.75 

42.73 

2.01 

1.89 

TABLE  81. — Sodium  Melachlorobenzoate. 


V 

A15° 

A25° 

A35° 

A15-250 

A25-350 

100 

15.53 

17.69 

19.82 

.39 

.20 

250 

19.74 

22.76 

25.80 

.53 

.34 

500 

22.83 

26.62 

30.59 

.66 

.49 

1,000 

25.60 

30.18 

35.15 

.79 

.65 

2,000 

27.38 

32.68 

38.36 

.94 

.74 

5,000 

29.55 

35.40 

41.81 

.98 

.81 

10,000 

30.51 

36.49 

43.40 

.96 

.89 

20,000 

31.01 

37.03 

43.87 

.94 

1.85 

V 

A15° 

A25° 

A35° 

A  15-25° 

A25-350 

100 

13.19 

14.84 

16.37 

.25 

.07 

250 

17.24 

19.60 

21.86 

.37 

.15 

500 

20.76 

23.94 

26.99 

.53 

.27 

1,000 

23  .  90 

27.82 

31.92 

.64 

.47 

2,000 

26.17 

30.81 

35.75 

.77 

.60 

5,000 

28.44 

33.54 

38.91 

.79 

.60 

10,000 

29.29 

34.71 

40.68 

.85 

.72 

20,000 

29.52 

34.82 

40.50 

.80 

.63 

TABLE  78. — Sodium  m-brombenzoatc >.. 


V 

A15° 

A25° 

A35° 

A15-250 

A25-350 

100 

14.64 

16.66 

18.67 

.38 

1.21 

250 

18.52 

21.35 

24.20 

.53 

1.33 

500 



1,000 

23.94 

28.20 

32.86 

.78 

1.65 

2,000 

25.55 

30.38 

35.80 

.89 

1.78 

5,000 

27.56 

32.85 

38  .  83 

.92 

1.82 

10,000 

28.30 

33  .  93 

40.20 

.99 

1.85 

20,000 

29.06 

34.71 

41.15 

1.94 

1.86 

TABLE  80. — Sodium  Orthochlorobenzoate . 


V 

A15° 

A25° 

A35° 

A15-250 

A25-350 

100 

14.54 

16.49 

18.34 

1.34 

.12 

250 

18.71 

21.52 

24.25 

1.50 

.27 

500 

21.90 

25.44 

29.09 

1.62 

.43 

1,000 

24.83 

29.23 

33.86 

1.77 

.58 

2,000 

26.85 

31.96 

37.42 

1.90 

.71 

5,000 

28.82 

34.65 

40.85 

2.02 

1.79 

10,000 

29.97 

36.04 

2.03 

.... 

20,000 

30.26 

36.76 

43.59 

2.15 

1.86 

TABLE  82. — Sodium  p-chlorobenzoaie. 


V 

A15° 

A25° 

A35° 

A15-250 

A25-350 

100 

15.80 

18.04 

20.22 

1.42 

1.21 

250 

19.92 

23.04 

26.18 

1.57 

1.36 

500 

22.91 

26.78 

30.90 

1.69 

1.54 

1,000 

25.65 

30.37 

35.39 

1.84 

1.65 

9  000 

5,000 

29.25 

35.27 

41.64 

2.06 

1.81 

10,000 

30.17 

(36.24) 

43.13 

(2.02) 

(1.90) 

20,000 

30.33 

36.80 

43.42 

2.13 

1.80 

112  Studies  on  Solution. 

TABLE  83.— Sodium  Salicylate.  TABLE  84.— Sodium  m-hydroxybenzoate. 


V 

A15° 

A25° 

A35° 

A15-250 

A25-350 

50 

14.19 

16.32 

18.42 

.51 

.29 

100 

17.19 

19.87 

22.58 

.56 

.36 

250 

21.52 

25.13 

28.84 

.67 

.48 

500 

24.56 

28.92 

33.60 

.78 

.62 

1-,000 

27.48 

32.62 

38.31 

.87 

.74 

2,000 

29.18 

34.87 

41.18 

.95 

.81 

2,500 

30.00 

35.92 

42.45 

1.97 

.82 

5,000 

31.20 

37.47 

44.57 

2.01 

.87 

10,000 

31.90 

38.38 

45.61 

2.03 

1.88 

20,000 

32.38 

38.99 

46.36 

2.04 

1.89 

TABLE  85. — Sodium  p-hydroxybenzoatc. 


V 

A15° 

A25° 

A35° 

A15-250 

A25-350 

50 

100 

12.54 

14.04 

15.21 

1.20 

0.83 

250 

16.63 

18.84 

20.93 

1.33 

1.11 

500 

19.39 

22.31 

25.21 

1.51 

1.30 

1,000 

22.31 

26.05 

29.85 

1.68 

1.46 

2,000 

24.17 

28.82 

33.50 

1.92 

1.62 

5,000 

26.27 

31.58 

36.73 

2.02 

1.63 

10,000 

27.28 

32.95 

38.74 

2.08 

1.76 

20,000 

27.34 

33.27 

(38.69) 

2.17 

TABLE  87. — Sodium  lodosalicylate. 


V 

A15° 

A25° 

A35° 

A15-250 

A25-350 

50 

100 
250 
500 
1,000 
2,000 
2,500 

17.66 
21.93 
25.07 
27.48 
29.24 

20.47 
25.67 
29.55 
32.67 
34.95 

23.44 
29.59 
34.49 
36.28 
41.23 

.59 
.71 
.79 
.89 
.95 

1.45 
1.53 
1.67 
1.73 
1.80 

5,000 
10,000 
20,000 

30.89 
31.38 
31.57 

37.17 
37.69 
38.35 

44.03 
45.08 

2.03 
2.01 
2.15 

1.85 
1.96 

TABLE  89. — Sodium  Orthonitrobenzoate. 


V 

A15° 

A25° 

A35° 

A15-250 

A25-350 

50 

11.81 

13.28 

14.62 

.24 

.01 

100 

14.79 

16.73 

18.59 

.31 

.11 

250 

18.94 

21.76 

24.45 

.49 

.24 

500 

22.13 

25.69 

29.34 

.61 

.42 

1,000 

24.87 

29.26 

33.82 

.77 

.56 

2,500 

27.60 

32.83 

38.51 

.89 

.73 

5,000 

29.10 

34.89 

41.29 

.99 

.83 

10,000 

30.04 

36.07 

42.89 

2.00 

.89 

V 

A15° 

A25° 

A35° 

A  15-25° 

A25-350 

50 

100 
250 
500 
1,000 
2,000 
2  500 

13.61 
17.64 

23!  61 
25.62 

15.31 
20.13 

27161 
30.27 

16.97 
22.51 

3l!85 
35.42 

1.25 
1.41 

i!e>9 

1.81 

1.08 
1.18 

1^54 
1.70 

5,000 
10,000 
20,000 

27.67 
28.33 
29.02 

32.88 
33.97 
34.65 

38.51 
39.98 
40.78 

1.S8 
1.99 
1.94 

1.71 
1.77 
1.77 

TABLE  86. — Sodium  Acetylsalicylale. 


V 

A15° 

A25° 

A35° 

A15-250 

A25-350 

50 

14.16 

16.29 

18.38 

.50 

.28 

100 

17.16 

19.81 

22.50 

.54 

.36 

250 

21.50 

25.08 

28.71 

.67 

.45 

500 

24.44 

28.73 

33.41 

.76 

.63 

1,000 

27.62 

32.76 

38.36 

.86 

.71 

2,500 

30.06 

35.89 

42.38 

.94 

.81 

5,000 

31.28 

37.44 

44.56 

.97 

.90 

10,000 

32.56 

38.97 

46.45 

.97 

.92 

25,000 

32.73 

39.17 

46.70 

.97 

.92 

TABLE  88. — Sodium  Sulphosalicylaie. 


V 

A15° 

A25° 

A35° 

A15-250 

A25-350 

50 

12.38 

14.28 

16.21 

1.53 

.35 

100 

15.30 

17.73 

20.29 

1.59 

.44 

250 

19.19 

22.48 

25.92 

1.71 

.53 

500 

21.92 

25.90 

30.22 

1.82 

.67 

1,000 

24.34 

29.00 

34.11 

1.95 

.76 

2,000 

26.12 

31.27 

37.11 

1.97 

.87 

2,500 

26.58 

31.93 

37.86 

2.01 

.86 

5,000 

28.18 

33.88 

40.42 

2.02 

.93 

10,000 

29.37 

35.47 

42.41 

2.08 

.97 

20,000 

30.65 

37.13 

44.16 

2.11 

.89 

TABLE  90. — Sodium  m-nitrobenzoate. 


V 

A15° 

A25° 

A35° 

A15-250 

A25-350 

50 

13.61 

15.55 

17.49 

.43 

.25 

100 

16.43 

16.94 

21.44 

.53 

.32 

250 

(20.13) 

(23.09) 

26.52 

(  .47) 

.49 

500 

23.32 

27.54 

31.95 

.81 

.60 

1,000 

26.16 

31.08 

36.44 

.88 

.72 

2,500 

28.41 

33.89 

40.05 

.93 

.82 

5,000 

29.52 

35.21 

42.12 

.93 

.96 

10,000 

29.80 

35.66 

42.95 

.97 

2.04 

Electrical  Conductance  in  Absolute  Ethyl  Alcohol.  113 

TABLE   91. — Sodium   Paranitrobenzoate.  TABLE  92. — Sodium  2,  4,  Dinitrobenzoate. 


V 

A15° 

A25° 

A35° 

A15-250 

25-35° 

50 

14.31 

16.47 

18.61 

.51 

1.30 

100 

17.22 

19.96 

22.72 

.59 

1.38 

250 

21  04 

28  19 

500 

23.98 

28.36 

33.09 

.83 

1.67 

1,000 

26.59 

31.69 

37.30 

.84 

1.77 

2,500 

28.63 

34.25 

40.51 

.96 

1.83 

5,000 

29.75 

35.66 

42.53 

1.99 

1.93 

10,000 

30.70 

36.98 

44.10 

2.05 

1.93 

TABLE  93. — Sodium  Orthotoluate. 


V 

A15° 

A25° 

A35° 

A15-250 

A25-350 

50 

11.42 

12.80 

14.11 

1.22 

1.01 

100 

14.19 

16.03 

17.81 

1.30 

.11 

250 

18.32 

21.07 

23.67 

.50 

.23 

500 

21.28 

24.69 

28.16 

.60 

.41 

1,000 

24.53 

28.80 

33.24 

.74 

.54 

2,500 

27.17 

32.19 

37.52 

.85 

.66 

5,000 

28.63 

34.23 

40.23 

.96 

.75 

10,000 

29.56 

35.36 

41.75 

.96 

.81 

25,000 

TABLE  95. — Sodium  Paratoluate. 


F 

A15° 

A25° 

A35° 

A15-250 

A25-350 

50 

11.25 

12.53 

13.74 

1.14 

0.96 

100 

14.05 

15.79 

17.43 

1.24 

1.04 

250 

18.11 

20.68 

23.00 

.42 

1.12 

500 

21.14 

24.45 

27.75 

.57 

1.35 

1,000 

24.15 

28.29 

32.55 

.71 

1.51 

2,500 

26.64 

31.46 

36.62 

.82 

1.64 

5,000 

28.00 

33.29 

39.21 

.89 

1.78 

10,000 

28.49 

33.80 

39.91 

.86 

1.81 

40,000 

V 

A15° 

A25° 

A35° 

A15-250 

A25-350 

100 

18.20 

21.09 

24.09 

1.59 

.42 

250 

22.18 

25.98 

29.93 

1.71 

.52 

500 

24.95 

29.45 

34.39 

1.80 

.69 

1,000 

27.41 

32.52 

38.33 

1.86 

.79 

2,000 

28.74 

34.42 

40.88 

1.98 

.88 

5,000 

30.45 

36.63 

43.71 

2.03 

.93 

10,000 

31.21 

37.66 

44.94 

2.07 

.93 

20,000 

31.80 

38.27 

45.86 

2.03 

.98 

TABLE  94. — Sodium  m-toluate. 


V 

A15° 

A25° 

A35° 

A15-250 

A25-350 

50 

11.16 

12.46 

13.64 

.16 

0.97 

100 

14.16 

15.92 

17.57 

.24 

1.04 

250 

18.26 

20.85 

23.32 

.42 

1.18 

500 

21.42 

24.75 

28.17 

.55 

1.38 

1,000 

24.10 

28.24 

32.55 

.72 

1.53 

2,500 

26.60 

31.52 

36.74 

.85 

1.66 

5,000 

27.97 

33.38 

39.36 

.93 

1.79 

10,000 

28.68 

34.24 

40.33 

.94 

1.78 

25,000 

29.36 

35.05 

41.22 

.94 

1.76 

TABLE  96. — Sodium  Picrate. 


V 

Alo° 

A25° 

A35° 

A  15-25° 

A25-350 

100 

19.77 

23.28 

27.09 

1.78 

1.64 

250 

24.49 

28.93 

33.80 

1.81 

1.68 

500 

27.81 

33.04 

38.79 

1.88 

1.74 

1,000 

30.65 

36.56 

43.24 

1.93 

1.83 

2,000 

32.78 

39.24 

46.60 

1.97 

1.88 

5,000 

34.73 

41.67 

49.85 

2.00 

1.96 

10,000 

35.73 

42.91 

51.46 

2.01 

1.99 

20,000 

36.32 

43.63 

52.43 

2.01 

2.02 

40,000 



43.86 



.... 

.... 

DISCUSSION  OF  RESULTS. 

The  most  apparent  observation  from  tables  65  to  96  is  the  great 
similarity  in  amount  of  conductance  of  these  organic  salts  in  alcohol. 
At  25°  in  a  1,000-liter  dilution  the  extreme  limits  for  the  conduct- 
ance are  from  26  to  36  mhos,  with  an  average  value  from  28  to  33. 
The  obvious  reason  for  this  is  the  uniform  effect  of  the  sodium  ion  in 
the  solution  and  the  similarity  in  the  velocities  of  the  organic  anions. 
As  naturally  expected,  the  conductances  of  these  salts  are  much 
greater  than  those  of  the  corresponding  acids. 

Very  little  can  be  said  as  to  the  relation  between  chemical  composi- 
tion and  conductance.  The  aliphatic  and  aromatic  derivatives  show  no 


114 


Studies  on  Solution. 


difference,  and  the  conductance  of  the  aromatic  compounds  seems  to  be 
independent  of  the  position  of  the  various  substituent  groups.  Sodium 
picrate  has  a  much  larger  conductance  than  any  other  salt,  and  the 
monosodiumsulphosalicylate  at  high  dilutions  gives  abnormally  large 
and  increasing  conductance  values,  due  probably  to  the  secondary 
ionization  of  the  carboxyl  group  at  these  high  dilutions. 

In  discussing  the  temperature  coefficient  of  conductance  it  is  to  be 
noticed  that  this  value  becomes  gradually  larger  with  increase  in 
dilution,  and  at  the  highest  dilutions  approximates  the  value  0.0200. 
Just  as  in  the  conductance  results,  there  is  here  no  definite  relation 
between  the  values  for  the  temperature  coefficient  and  chemical 
composition. 

It  is  of  importance  to  note  that  this  work  on  the  sodium  salts  of 
the  organic  acids  in  absolute  alcohol  has  been  greatly  restricted,  owing 
to  the  almost  complete  insolubility  of  a  great  many  of  these  salts  in 
this  solvent.  If  the  work  were  carried  out  in  alcohol  which  was  not 
absolute,  practically  all  the  salts  could  be  studied,  for  it  is  necessary  to 
add  only  a  very  small  amount  of  water  to  obtain  a  sufficient  degree  of 
solubility.  We  have  approximately  covered  the  field  of  available 
compounds.  It  is  of  interest  to  note  that  the  polybasic  acids  of  both 
the  aliphatic  and  aromatic  series  are  excluded  from  study  for  this 
reason,  as  well  as  all  unsaturated  acids  of  both  series.  A  number  of 
salts  of  aromatic  acids  with  di-  and  tri-substitutions  in  the  ring  were 
likewise  impossible  to  study. 

Reference  has  already  been  made  (see  pages  100-103)  to  the  work 
of  Heinrich  Goldschmidt  on  the  conductance  of  alcoholic  solutions  of 
sodium  salts.  We  have  purposely  investigated  most  of  the  salts  which 
he  studied.  A  comparison  of  these  results  is  conveniently  made  by 
reference  to  the  following  tables : 


Salt. 

Goldschmidt. 

Authors. 

Sodium  dichloroacetate.  .  . 
Sodium  trichloroacetate  .  . 
Sodium  salicylate  
Sodium  sulphosalicylatc  .  . 
Sodium  picrate  

Table  60,  p.  100 
59,  100 
61,  101 
62,  101 
63,  101 

Table  68,  p.  110 
69,  110 
83,  112 
88,  112 
96,  113 

It  can  be  seen  from  these  tables  that  the  two  series  of  conductance 
values  are  in  accordance,  but  an  exact  comparison  can  not  be  made 
because  of  the  fact  that  the  values  of  A  in  the  two  series  refer  to  some- 
what different  concentrations.  In  order  to  make  an  effective  com- 
parison we  have  plotted  the  values  of  A  against  the  logarithms  of  the 
volume  V  in  the  case  of  sodium  trichloroacetate  (see  fig.  26).  The 
points  circled  refer  to  the  data  of  Goldschmidt  and  the  crosses  to 


Electrical  Conductance  in  Absolute  Ethyl  Alcohol. 


115 


data  obtained  in  the  present  work.  With  few  exceptions  all  the  points 
lie  on  one  curve,  and  the  slight  deviations  which  occur  are  within  the 
limits  of  error  of  the  conductance  method.  The  four  other  salts  give 
similar  results;  therefore  their  graphs  are  omitted. 


44- 
4-0 
36 
32 
28 

A 

24 

20 
16 


LogV 

FIG.  26. — Comparison  of  Conductance  Values  in  Absolute  Alcohol. 
o  =  Goldschmidt;  x  =  Lloyd  and  Pardee. 

It  has  been  found  impossible  to  obtain,  experimentally,  a  value  for 
the  limiting  conductance,  although  measurements  have  been  carried 
out  to  10,000  and  20,000  liter  dilutions.  It  is  therefore  necessary 
to  determine  A0  by  some  method  of  extrapolation.  It  will  be  recalled 
that  Goldschmidt  used  the  Kohlrausch  formula  for  this  purpose  (see 
page  101),  although  its  applicability  to  alcoholic  solutions  and  even 
to  aqueous  solutions1  had  been  previously  questioned.  We  applied 
this  formula  to  our  experimental  data  with  a  similarly  unsatisfactory 
result.  The  calculated  values  of  A0  vary  to  such  an  extent  that  it  is 
impossible  to  make  a  selection. 

A  function  of  another  form,  suggested  by  A.  A.  Noyes,2  which  has 
been  successfully  used  in  connection  with  researches  upon  the  electrical 

*A.  A.  Noyes:  Journ.  Amer.  Chem.  Soc.  30,  344  (1908). 
2Journ.  Amer.  Chem.  Soc.  30,  335  (1908). 


116  Studies  on  Solution. 

conductance  of  aqueous  solutions,  presented  a  possible  means  of  deter- 
mining AO  in  alcoholic  solutions.     This  function  has  the  form 


where  A  is  the  equivalent  conductance  at  the  concentration  c  (  1  /  V)  .  K 
is  a  constant,  and  n  is  a  number  which,  for  aqueous  solutions,  lies 
between  1.3  and  1.7.  The  value  of  n  is  so  chosen  that  the  graph 
obtained  by  plotting  the  reciprocal  of  the  equivalent  conductance 
(I/A)  at  the  various  concentrations  (c)  against  (cA)n-1  is  nearly  a 
straight  line.  Two  other  graphs  corresponding  to  neighboring  values 
of  n,  on  opposite  sides  of  the  first  line,  are  also  drawn  so  as  to  aid  in 
determining  the  most  probable  point  at  which  the  graphs  cut  the 
I/A  axis.1  This  point  is  1/A0,  the  reciprocal  of  the  limiting  conduc- 
tivity. 

This  procedure  was  followed,  using  the  data  at  25°  of  sodium  tri- 
chloroacetate,  salicylate,  orthonitrobenzoate,  2,  4  dinitrobenzoate, 
and  picrate.  The  graphs  obtained  are  in  every  respect  similar  to  those 
for  aqueous  solutions,  except  that  the  value  of  n  lies  between  1.7  and 
1.8.  The  values  of  Ao  obtained  for  the  above  salts  at  25°  are: 

Sodium  trichloroacetate  .........................     41  .  6 

Sodium  salicylate  ................................  39.9 

Sodium  orthonitrobenzoate  .......................  38  .  0 

Sodium  2,  4  dinitrobenzoate  ......................  39.2 

Sodium  picrate  ..................................  44.  7 

From  these  figures  the  percentage  dissociation  of  these  salts  is  obtained 

by  means  of  the  familiar  formula  a  =  T— 

A0 

While  the  procedure  outlined  above  is  thus  proved  to  give  satisfactory 
results  hi  alcoholic  solutions,  the  calculations  are  quite  laborious,  and 
advantage  is  taken  of  a  much  shorter  method  of  approximating  A0, 
suggested  by  Randall.2  It  is  a  fact  that  as  the  zero  of  concentration 
(infinite  dilution)  is  approached,  the  difference  in  the  percentage 
ionization  of  all  salts  approaches  zero. 

Randall  makes  the  provisional  assumption  that  the  ionization  of 
salts  of  the  same  type  (such  as  thallous  chloride  and  potassium  chloride) 
is  the  same.  Knowing  the  percentage  dissociation  of  potassium 
chloride  at  various  dilutions  very  accurately,  he  calculates  the  value  of 
A0  for  thallous  chloride  by  means  of  the  equation 

A0=A/a' 

in  which  a'  is  the  percentage  dissociation  of  KC1  at  any  given  dilution 
and  A  is  the  molecular  conductance  of  T1C1  at  the  same  dilution. 
Such  a  calculation  gives  values  for  A0  which  approach  a  constant  figure 
with  increasing  dilution. 


.  Johnston:  Journ.  Amer.  Chem.  Soc.  31,  1010  (1909). 
2Journ.  Amer.  Chem.  Soc.  38,  788  (1916). 


Electrical  Conductance  in  Absolute  Ethyl  Alcohol. 


117 


In  applying  this  method  to  our  results  we  have  made  use  of  the 
values  of  percentage  dissociation  obtained  by  means  of  the  equation  of 
Noyes.  It  has  been  found  that  the  three  salts,  sodium  trichloroacetate, 
salicylate,  and  orthonitrobenzoate,  include  examples  of  all  the  various 
types  of  salts  encountered  in  the  present  investigation. 

The  calculation  of  A0  is  illustrated  by  table  97 

TABLE  97. 


y 

100  a  25° 

A  25° 

A  Sodium  Acetate. 

Sodium  Salicylate. 

Sodium  Acetate. 

a  Sodium  Salicylate. 

100 

49.8 

17.20 

34.5 

250 

63.0 

22.20 

35.2 

500 

72.5 

26.97 

35.9 

1,000 

81.8 

29.99 

36.6 

2,000 

87.4 

32.80 

37.5 

5,000 

94.0 

35.42 

37.7 

10,000 

96.3 

36.36 

37.8 

20,000 

97.8 

36.79 

37.7 

Probable  Ao  =37.8. 

Table  98  contains  the  most  probable  values  of  A0  at  25°  for  all  the 
salts  studied  by  the  authors  and  calculated  in  the  manner  just  indi- 
cated. 

TABLE  98. 


Sodium. 

Ao 

Sodium. 

Ao 

Sodium. 

Ao 

Formate  

40.7 

Orthoamidobenzoate  .  . 

36.6 

lodosalicylate  

39  2 

Acetate 

37  8 

Para-amidobenzoate 

35  0 

Sulphosalicylate 

Chloroacetate 

39  5 

Metabrombenzoate 

35  6 

Orthonitrobenzoate 

38  0 

Dichloroacetate  
Trichloroacetate  
Phenylacetate  
Propionate  
/3-iodopropionate    . 

41.6 
41.6 
35.6 
37.3 
40  2 

Parabrombenzoate  .... 
Orthochlorobenzoate  .  . 
Metachlorobcnzoate  .  . 
Parachlorobenzoate  .  .  . 
Salicvlate 

36.9 
37.9 
38.0 
37.9 
39  9 

Metanitrobenzoate  .  . 
Paranitrobenzoate  .  .  . 
2,  4  dinitrobenzoate  .  . 
Orthotoluate  
Metatoluate 

37.3 
38.7 
39.2 
37.0 
35  7 

Butyrate  

37  0 

Metahydroxybenzoate. 

35  7 

Paratoluate 

35  6 

Oxyisobutyrate  

37  6 

Parahydroxybcnzoate 

35  0 

Picrate 

44  7 

Benzoate  

37  4 

Acetylsalicvlate 

39  9 

The  values  of  A0  for  the  organic  acids  are  calculated  from  those 
of  the  sodium  salts  by  means  of  the  following  equation: 
AO  acid=A0Na  salt+A0HCl-A0NaCl 

The  values  of  A0HC1  and  A0NaCl  have  been  obtained  from  the 
conductance  data  of  Goldschmidt1  by  means  of  the  equations  of  Noyes 
and  of  Randall.  A0HC1  can  be  very  precisely  fixed  at  82.0  mhos. 
A0NcCl  is  most  probably  42.0  mhos,  with  a  possible  variation  of  =±=0.5 
mho.  Substituting  these  values  in  the  equation  above,  we  have 

A0  acid=A0Na  salt +40 

physik  Chem.  89,  131,  142  (1914). 


118 


Studies  on  Solution. 


Table  99  contains  the  probable  values  of  A0  at  25°  for  the  organic 
acids,  calculated  in  the  manner  just  indicated. 


TABLE  99. 


Acid. 

Ao 

Acid. 

Ao 

Acid. 

Ao 

Formic  
Acetic 

80.5 
78  0 

Orthoamidobenzoic  .  .  . 
Meta~amidobenzoic  .  .  . 

76.5 
75.0 

lode-salicylic  
Sulphosalicylic  

79.0 

Chloroacetic 

79.5 

Para-amidobenzoic  .  .  . 

75.5 

Orthonitrobenzoic  .  .  . 

78.0 

Dichloroacetic 

81.5 

Orthochlorobenzoic  .  .  . 

77.5 

Metanitrobenzoic  .... 

77.5 

Trichloroacetic  
Phenylacetic         .... 

81.5 
75.5 

Metachlorobenzoic  
Parachlorobenzoic  .... 

78.0 
78.0 

Paranitrobenzoic  .... 
2,  4  dinitrobenzoic  .  .  . 

78.5 
79.0 

Propionic 

77  5 

Salicylic  

80.0 

Orthotoluic  

77.0 

/3-:odopropionic  
Butyric 

80.0 
77  0 

Metahydroxybenzoic.  . 
Parahydroxybenzoic.  . 

75.5 
75.0 

Metatoluic  
Paratoluic  

75.5 
75.5 

77  5 

Acetylsalicvlic 

80  0 

Picric 

84  5 

Benzoic 

77.5 

SUMMARY. 

The  authors  have  prepared  absolute  alcohol  solutions  of  32  sodium 
salts  of  organic  acids,  and  have  measured  the  electrical  conductance  of 
these  solutions  at  15°,  25°,  and  35°,  over  a  concentration  range  extend- 
ing from  N/50  to  N/20000.  Five  of  the  salts  had  been  previously 
studied  by  Goldschmidt  and  his  pupils,  and  our  results  present  a 
striking  confirmation  of  their  data. 

The  A0  values  for  the  salts  can  not  be  obtained  experimentally, 
although  they  may  be  closely  approached  in  many  instances;  they  must 
therefore  be  obtained  by  some  method  of  extrapolation.  Goldschmidt 
used  the  Kohlrausch  formula 


In  common  with  Turner  and  with  Dutoit  and  Rappeport  we  have  been 
unable  to  get  satisfactory  results  with  this  formula.  We  have  been 
entirely  successful,  however,  in  the  use  of  a  function  developed  for 
aqueous  solutions  by  A.  A.  Noyes  and  J.  Johnston: 


By  means  of  this  function  we  have  obtained  the  A0  values  at  25°  for 
all  of  the  salts  which  have  been  studied.  By  combining  these  values 
with  A0HC1  and  A0NaCl  we  have  been  able  to  calculate  the  limiting 
conductance  at  25°  of  31  organic  acids  in  absolute  alcohol  solution. 
These  A0  values,  in  the  case  of  the  5  acids  studied  also  by  Goldschmidt, 
are  uniformly  lower  than  those  obtained  by  the  latter. 

With  a  knowledge  of  the  A0  values  of  the  organic  acids,  it  will  be 
possible  to  estimate  the  dissociation  and  affinity  constants  of  these 
acids  in  absolute  alcohol  solution. 


CHAPTER  V. 

A  STUDY  OF  THE  DISSOCIATING  POWERS  OF  FREE  AND  OF  COMBINED 

WATER. 


BY  G.  FRED.  ORDEMAN. 


INTRODUCTION. 

The  work  of  Uhler,1  Anderson,2  Strong,3  Guy  and  Shaeffer,4  and 
Paulus5  on  the  absorption  spectra  of  solutions  in  their  relation  to  the 
phenomenon  of  solvation  has  been  reviewed  in  a  preliminary  paper  on 
this  subject.6  These  investigators  having  found  a  marked  physical 
difference  between  free  water  and  combined  or  water  of  hydration  in 
their  behavior  towards  light,  it  was  believed  that  a  determination  of  the 
dissociation  power  of  this  combined  water  might  lead  to  the  establish- 
ment of  further  differences  between  it  and  free  water.  A  few  prelim- 
inary measurements  showed  the  probability  of  such  a  difference  in 
dissociating  power.  The  present  investigation  is  a  continuation  of 
this  work  along  somewhat  broader  lines.  For  the  sake  of  completeness, 
certain  details  of  the  method,  although  described  in  the  preliminary 
paper,  are  repeated  here.  The  object  has  been  to  ascertain  the  differ- 
ence, if  any,  between  the  dissociating  power  of  combined  water  or 
water  of  hydration  and  the  dissociating  power  of  uncombined  or  free 
water. 

EXPERIMENTAL. 
APPARATUS. 

Conductivity  Apparatus. — The  improved  slide- wire  bridge  used  for 
the  conductivity  measurements  was  manufactured  by  The  Leeds  and 
Northrup  Company,  of  Philadelphia.  In  this  instrument  the  resist- 
ance wire,  5  meters  in  length,  is  wrapped  around  a  porcelain  drum. 
Readings  were  made  corresponding  in  most  cases  to  at  least  0.25  mm. 
The  resistance  box  had  been  standardized  by  the  Bureau  of  Standards, 
Washington.  An  alternating  current  was  supplied  by  an  induction 
coil  specially  constructed  for  such  work.  The  coil  was  actuated  by  a 
single  lead  accumulator  and  the  strength  of  the  current  was  regulated 
by  adjusting  the  length  of  a  thin  manganin  wire  inserted  between 
battery  and  coil.  A  telephone  receiver  was  employed  to  determine  the 
point  of  equilibrium.  A  double  system  of  wiring  was  used  between  the 

'Carnegie  Inst.  Wash.  Pub.  No.  60, 160  (1907).     3Ibid.,  130  (1910).        5Ibid,  210,  9  (1915). 
.,  110  (1909).  *Ibid.,  190  (1913).        *IUd,  230,  161  (1915). 

119 


120  Studies  on  Solution. 

rheostat,  bridge,  and  cell.  Thus,  by  means  of  a  rocking  commu- 
tator with  mercury  contacts,  the  positions  of  rheostat  and  cell  relative 
to  the  bridge  could  be  interchanged  so  that  both  a  and  b  could  be  read 
directly.  All  copper  wire  in  the  external  circuit  was  of  such  a  gage 
that  the  resistance  was  negligible.  All  connections  were  soldered. 

Cells. — Because  of  the  high  resistance  of  the  water  used  a  special 
" water  cell"1  having  large  electrodes  was  necessary.  The  electrodes 
consist  of  two  concentric  platinum  cylinders  held  in  position  by  small 
drops  of  fusion  glass  in  such  a  manner  that  they  are  about  1  mm.  apart. 

Because  of  the  large  conductivity  of  the  solutions  measured  a  differ- 
ent type  of  cell  was  demanded.  The  cell  finally  adopted  for  this  work 
was  that  which  has  been  previously  used  in  this  laboratory2  for  measure- 
ments of  the  conductivity  of  concentrated  solutions.  It  consisted  of 
a  U-shaped  tube  made  of  difficultly  soluble  glass  and  fit  ted  with  ground- 
glass  stoppers.  A  glass  tube  carrying  a  small  platinum  electrode  is 
sealed  by  means  of  sealing-wax  into  the  hole  bored  in  the  center  of  each 
stopper.  The  tubes  were  first  held  in  position  by  tamping  wet  asbestos 
between  them  and  the  walls  of  the  stoppers.  The  distance  between  the 
electrodes  can  be  changed  by  removing  the  wax,  adjusting  the  tubes, 
and  resealing.  The  platinum  plates  are  coated  with  platinum  black. 
Numbers  are  etched  upon  the  stoppers  and  the  corresponding  arms  of 
the  U-tubes,  so  that  the  electrodes  will  always  be  placed  in  th9  same 
U-tube  and  in  the  same  position. 

Constant  Temperature  Bath. — A  constant  temperature  was  main- 
tained by  the  application  of  a  principle  most  clearly  stated  by  Morse  :3 

"If  all  the  water  or  air  in  a  bath  is  made  to  pass  rapidly  (1)  over  a  continu- 
ously cooled  surface  which  is  capable  of  reducing  the  temperature  slightly 
below  that  which  it  is  desired  to  maintain,  then  (2)  over  a  heated  surface  which 
is  more  efficient  than  the  cooled  one  but  which  is  under  the  control  of  a  thermo- 
stat, and  (3)  again  over  the  cooled  surface,  etc.,  it  should  be  practicable  to 
maintain  in  the  bath  any  temperature  for  which  the  thermostat  is  set,  and 
the  constancy  of  the  temperature  should  depend  only  on  the  sensitiveness  of 
the  thermostat  and  the  rate  of  flow  of  the  water  or  air." 

The  bath  used  is  fully  described  by  Davis  and  Putnam.4  By  means 
of  an  improved  toluene-mercury  thermo-regulator5  and  an  electrically 
controlled  gas  valve6  the  temperature  was  maintained  constant  to 
within  0.01°. 

A  Beckmann  thermometer  graduated  to  0.05°  was  used  in  the  bath. 
Comparison  was  made  with  a  thermometer  recently  standardized  at 
the  Bureau  of  Standards,  Washington. 

Glassware. — Measuring  flasks,  burettes,  and  pipettes  were  recali- 
brated by  direct  weighing.  Jena  glass  bottles  were  used  for  keeping 
the  solutions. 

lCarnegie  lust.  Wash.  Pub.  No.  180,  89  (1913);  Amer.  Chem.  Journ.,  45,  282  (1911). 

2Zeit.  physik.  Chem.,  49,  389  (1904).  Carnegie Inst.  Wash. Pub.  No. 210, 119  (1915). 

'Carnegie  Inst.  Wash.  Pub.  No.  198, 56  (1914).     6/6iW.,230, 13(1915).         «Ibid.,2W,  121  (1915). 


The  Dissociating  Powers  of  Free  and  of  Combined  Water.  121 

SOLVENTS. 

Water.  —  The  water  was  purified  by  the  method  of  Jones  and  Mackay1 
as  modified  by  Schmidt/*  and  had  a  mean  specific  conductivity  of  1.8  X 
10~6  at  25°  C. 

Isohydric  Solutions.  —  If  two  solutions  of  electrolytes  are  mixed  the 
conductivity  of  the  mixture  is,  in  general,  less  than  the  mean  of  the 
conductivities  of  the  constituents.  If  the  two  solutions  contain  a 
common  ion,  however,  there  are  concentrations  at  which  they  can  be 
mixed  without  affecting  each  other's  conductivity.  This  fact  was  first 
explained  by  Arrhenius.3  He  showed  that  if  equal  volumes  of  two 
solutions  of  acids  of  certain  concentrations  be  mixed,  the  conductivity 
of  the  mixture  is  the  mean  of  the  conductivities  of  the  solutions,  pro- 
vided there  be  no  appreciable  change  in  volume.  Such  solutions  are 
said  to  be  isohydric.  Arrhenius4  defines  them  as  follows: 

"Two  solutions  of  acids  are  isohydric  whose  conductivity,  or  in  other  words, 
whose  electrolytic  dissociation,  is  not  changed  if  they  are  mixed." 

Arrhenius  worked  out  the  condition  for  two  solutions  containing  a 
common  ion  to  be  isohydric  and  has  expressed  it  thus: 


In  this  equation,  a  =  percentage  dissociation  of  the  salt  in  solution, 
Vi  =  number  of  liters  of  solution  containing  a  gram-molecular  weight  of 
the  salt,  m  =  number  of  common  ions  in  each  molecule  of  the  salt. 
|3,  #2,  and  n  are  the  respective  symbols  for  the  second  solution. 

It  was  further  shown  by  Arrhenius  that  two  acids  are  isohydric  if  in  a 
unit  volume  they  contain  the  same  number  of  hydrogen  ions.  With 
this  principle  in  mind  the  investigator,  in  the  course  of  his  work, 
determined  the  concentrations  of  five  different  pairs  of  salt  solutions 
when  they  fulfill  the  condition  of  being  isohydric.  This  method 
follows. 

In  calculating  the  percentage  dissociation  by  the  conductivity 
method 

"  tt=~         '-  2 


Here,  ju'  and  M"  =  molecular  conductivities  of  the  two  solutions; 
and  //OQ  =  the  conductivities  at  infinite  dilution. 

From  the  method  of  Kohlrausch  for  calculating  conductivity 


(3) 


1Amer.  Chem.  Journ.,  19,  90  (1897).  3Wied.  Ann.,  30,  51  (1887). 

2Carnegie  Inst.  Wash.  Pub.  No.  180,  135  (1913).          4Zeit.  physik.  Chem.,  2,  284  (1888). 


122  Studies  on  Solution. 

ki  and  k%  are  cell  constants,    -oi,  61,  and  02  and  62  are  the  respective 
readings  on  the  bridge  for  the  resistances  w\  and  w2. 
Substituting  the  values  of  (3)  in  (2),  we  obtain 

(4) 


Substituting  now  the  values  of  (4)  in  (1) 
m  k\a\v\  _  n 


(5) 

If  the  same  cell  be  used  in  determining  the  conductivities  of  the  two 
solutions,  then  k\  equals  k2,  and  simplifying  (5)  we  obtain 

mttl          Ua*  (6) 


This  is  the  general  equation,  which  becomes  further  simplified  for  a 
particular  case.    A  single  illustration  will  make  its  meaning  clear. 

What  concentration  is  necessary  for  a  calcium  nitrate  solution  that 
it  be  isohydric  with  regard  to  a  molar  solution  of  potassium  nitrate? 
At  25°  C.,  and  this  temperature  was  used  throughout  the  work,  for 
calcium  nitrate,  M'OO  equals  257.99,1  and  for  potassium  nitrate,  //'«> 
equals  148.39.  Considering  the  nitrate  ion,  m  =  2  and  n  =  1  .  Therefore 

2  ai  a2 


257.99  biWi     148.39  b2w2 
Whence 


b\w\  b2w2 

Now  by  measuring  a  and  b  of  the  molar  solution  of  potassium  nitrate 
for  the  resistance  w2,  the  right-hand  side  of  the  equation  becomes  a 
constant.  A  concentrated  solution  of  calcium  nitrate  was  taken  in 
different  portions  and  diluted  until,  by  trial,  that  concentration  was 

found  such  that  -^-  became  equal  to  the  value  for  the  right-hand  side 

Mi 
of  the  equation. 

The  concentration  of  the  calcium  nitrate  was  found  to  be  0.698 
molar.  And  so  a  calcium  nitrate  solution  of  this  concentration  contains 
the  same  number  of  nitrate  ions  per  unit  volume  as  a  molar  solution 
of  potassium  nitrate. 

SALTS. 

The  majority  of  the  salts  used  were  the  purest  obtainable  from 
Kahlbaum.  All  the  non-hydrated  salts  were  carefully  recrystallized 
from  conductivity  water  and  thoroughly  dried  at  the  temperature  best 

1M\  MOO  values  were  taken  from  Carnegie  Inst.  Wash.  Pub.  No.  170  (1912),  but  are  expressed 
here  in  reciprocal  ohms  instead  of  in  Siemens  units. 


The  Dissociating  Powers  of  Free  and  of  Combined  Waters.  123 

suited  to  each  salt.  The  hydra  ted  salts,  being  so  soluble,  were  in  most 
cases  not  recrystallized,  but  dissolved  in  conductivity  water,  filtered, 
and  used  as  concentrated  solutions. 

SOLUTIONS. 

Solutions  for  the  first  three  salts  in  table  100  were  made  as  follows. 
Quantities  of  the  isohydric  solutions  of  the  two  chlorides  were  made. 
The  amount  of  added  salt  necessary  for  each  concentration  was  weighed 
upon  a  watch  glass  and  introduced  into  a  calibrated  flask  through  a 
short-stemmed  funnel.  The  salt  was  dissolved  by  one  of  the  isohydric 
solutions  and  the  flask  placed  in  the  bath  regulated  for  25°  C.  When 
the  solution  had  come  to  temperature  it  was  diluted  to  the  mark  with 
more  of  the  isohydric  solution.  The  process  was  now  repeated,  using 
the  same  flask  and  the  other  isohydric  solution.  But  it  was  found  that 
the  volume  change  caused  by  the  added  salts  was  considerable.  This 
means  that  the  solutions  when  made  would  be  of  the  proper  strength 
for  the  added  salt  but  weaker  for  the  isohydric  solutions.  The  results 
are,  however,  still  comparable,  as  the  volume  change  in  the  two  iso- 
hydric solutions  was  found  to  be  about  the  same. 

Solutions  for  the  other  three  salts  in  table  100  were  made  in  a  dif- 
ferent manner.  Instead  of  using  the  stock  isohydric  solutions,  they 
were  made  up  as  needed.  The  amount  of  potassium  chloride  necessary 
to  make  the  isohydric  solution  molar  was  weighed  into  the  flask. 
The  added  salt,  being  a  hydrated  one,  could  not  be  weighed  directly. 
It  was  added  in  the  form  of  a  concentrated  solution  of  known  strength 
from  a  small  burette.  The  solutions  were  finally  brought  to  the  mark 
with  conductivity  water.  For  a  comparable  solution  the  necessary 
number  of  cubic  centimeters  of  a  concentrated  calcium  chloride  solu- 
tion of  known  strength  to  make  the  solution  0.6951  molar  was  used  in 
place  of  potassium  chloride.  In  this  way  solutions  were  obtained 
accurate  with  respect  to  the  isohydric  solutions  but  not  with  regard  to 
the  added  salt,  because  of  the  errors  due  to  improper  drainage  of  con- 
centrated solutions  in  a  burette  of  such  small  bore. 

It  was  finally  decided  to  take  the  densities  of  the  various  concen- 
trated solutions  and  to  add  these  solutions  by  weight  rather  than  by 
volume.  The  densities  were  taken  with  a  pycnometer.  The  solutions 
were  added  to  the  weighed  flasks  (capacity  25  c.c.)  from  a  burette  with 
a  finely  drawn  tip.  With  care  the  solutions  could  be  weighed  to 
within  1  or  2  mg.,  and  this  proved  to  be  the  most  accurate  method  of 
handling  these  salts.  As  before  the  same  flask  was  used  for  comparable 
solutions  and  the  possibility  of  errors  was  thus,  in  part,  avoided. 

The  strengths  of  the  different  concentrated  solutions  of  the  chlorides 
were  determined  by  an  estimation  of  the  chlorine  as  silver  chloride. 
The  other  concentrated  solutions  were  analyzed  for  the  cations.  All 
solutions  were  made  up  at  25°  C. 


124  Studies  on  Solution. 

PROCEDURE. 

Six  U-shaped  cells  were  used  in  this  work.  Five  of  them  had  con- 
stants in  the  neighborhood  of  14,000,  while  the  sixth  cell  had  a  constant 
of  29,941.  The  constants  were  determined  by  means  of  a  half-molar 
solution  of  potassium  chloride.  The  molecular  conductivity  of  this 
solution  was  found  to  be  115.71  reciprocal  ohms  at  25°  C. 

Two  solutions  were  first  made  isohydric  by  the  means  described 
above.  The  specific  conductivities  of  these  solutions  were  measured 

by  the  usual  method  and  calculated  from  the  formula  s  =  k  r—    The 

same  cell  was  employed  for  both  solutions,  so  that  any  change  in  the 
cell  constant  or  any  error  in  its  determination  would  be  eliminated  for 
comparison.  Pairs  of  solutions  were  made  which  were  isohydric  with 
regard  to  each  other  and  of  a  known  molarity  for  an  added  salt.  Three 
concentrations  of  each  added  salt  were  used.  The  specific  conduc- 
tivities of  these  solutions  were  now  determined.  When  the  conduc- 
tivity of  a  solution,  say  molar  with  regard  to  potassium  nitrate  and 
half-molar  with  regard  to  sodium  nitrate,  had  been  measured,  the  cell 
was  thoroughly  cleaned  and  dried.  The  same  cell  was  now  used  for 
the  determination  of  the  conductivity  of  a  solution  0.6984  molar  with 
respect  to  calcium  nitrate — that  is,  isohydric  with  potassium  nitrate 
and  half-molar  in  regards  to  sodium  nitrate.  Thus  possible  errors 
were  avoided. 

The  increase  in  conductivity  of  each  isohydric  solution  was  calculated 
for  each  added  salt  at  every  concentration  and  results  are  given  in  the 
third  and  fifth  columns  of  each  of  the  following  tables.  The  difference 
between  the  increases  for  comparable  solutions  is  found  in  the  last 
column  of  each  table.  At  the  top  of  each  table  the  concentrations  of 
the  two  solutions  which  were  isohydric  are  given. 

In  all  cases  the  numbers  given  for  conductivities  are  in  reciprocal 
ohms  and  represent  the  mean  of  at  least  three  readings  on  the  bridge 
for  different  resistances. 


The  Dissociating  Powers  of  Free  and  of  Combined  Water.  125 


MEASUREMENTS. 

The  headings  in  tables  100  to  104  require  some  explanation.  The 
two  main  headings  in  each  table  are  the  concentrations  of  the  two  solu- 
tions which  were  made  isohydric;  s  and  s'  are  the  specific  conductivi- 
ties of  solutions,  say  for  111.78  in  table  100,  molar  for  KC1  and  eighth- 
molar  for  NaCl.  As  and  As'  are  the  results  obtained  by  subtracting 
from  s  and  sf  the  specific  conductivities  of  the  corresponding  isohydric 
solutions.  As— As'  is  the  difference  in  the  increases  As  and  As'. 

TABLE  100. 
Molar  for  KC1;  0.695  molar  for  CaCl2. 


Added 
salt. 

V 

s 

As 

s' 

As' 

s-As' 

NaCl 

8 

118.82 

8.70 

106.91 

7.92 

0.78 

NaCl 

2 

144.33 

34.21 

127.91 

28.92 

5.28 

NaCl 

1 

172.30 

62.17 

151.66 

52.67 

9.50 

KC1 

8 

122.65 

12.52 

109.86 

10.87 

1.65 

KC1 

2 

158.12 

47.99 

140.91 

41.92 

6.07 

KC1 

1 

203.76 

93.63 

180.69 

81.70 

11.93 

NH4C1 

8 

122.56 

12.44 

109.75 

10.77 

1.67 

NH4C1 

2 

157.59 

47.46 

140.38 

41.29 

6.18 

NH4C1 

1 

202.12 

91.99 

180.69 

81.70 

10.29 

MgCl2 

8 

124.39 

14.27 

110.58 

11.60 

2.67 

MgCl2 

2 

157.44 

47.31 

139.66 

40.67 

6.64 

MgCl2 

1 

185.54 

75.41 

158.21 

59.22 

16.19 

CaCl2 

8 

126.47 

16.34 

112.39 

13.40 

2.93 

CaCl2 

2 

166.88 

56.75 

147.27 

48.28 

8.47 

CaCl2 

1 

204.78 

94.65 

177.69 

78.70 

15.95 

SrCl2 

8 

125  .  82 

15.69 

112.43 

13.45 

2.24 

SrCl2 

2 

166.13 

56.00 

145.86 

46.88 

9.12 

SrCl2 

1 

204.47 

94.34 

177.83 

78.84 

15.50 

I 

TABLE  101. 
Molar  for  NaCl;  0.597  molar  for  CaCl. 


Added 
salt. 

V 

s 

As 

9» 

As' 

As  -As' 

NaCl 

8 

93.21 

8.87 

97.38 

8.59 

0.28 

NaCl 

8 

117.77 

33.42 

119.70 

30.91 

2.51 

NaCl 

1 

146.76 

62.41 

147.31 

58.52 

3.89 

NH4C1 

8 

97.17 

12.82 

99.67 

10.87 

1.95 

NH4C1 

2 

132.59 

48.24 

133.06 

44.26 

3.98 

NH4C1 

1 

177.05 

92.70 

175.16 

86.37 

6.33 

MgCl2 

8 

98.05 

13.70 

101.16 

12.36 

1.34 

MgCl2 

2 

129.95 

45.60 

129  .  80 

41.01 

4.59 

MgCl2 

1 

157.52 

73.17 

164.44 

65.65 

7.52 

CaCl2 

8 

99.37 

15.02 

102.72 

13.93 

1.09 

CaCl2 

2 

138.24 

53.89 

138.73 

49.94 

3.95 

CaCl2 

2 

175.42 

91.07 

172.73 

83.93 

7.13 

SrCl2 

8 

99.79 

15.45 

103.16 

14.37 

1.07 

SrCl2 

2 

138.74 

54.39 

139.10 

50.31 

4.08 

SrCl2 

1 

175.88 

91.53 

110.22 

85.21 

6.32 

KNO3 

8 

94.69 

10.34 

98.17 

99.38 

0.97 

KNO3 

2 

122  .  59 

38.24 

122.52 

33.73 

4.51 

KNO3 

1 

156.38 

72.03 

151.31 

62.52 

9.51 

126 


Studies  on  Solution. 


TABLE  102. 

Molar  for  NaNO8;  0.681  molar  for  Ca(NO3),. 


Added 

salt. 

V 

1 

A* 

sf 

As' 

As  -As' 

NaNO3 

8 

81.77 

7.25 

83.53 

6.06 

1.19 

NaNO3 

2 

101.13 

26.62 

98.83 

21.36 

5.26 

NaN03 

1 

123.40 

48.89 

116.71 

39.24 

9.65 

KNO3 

8 

83.49 

8.97 

84.92 

7.45 

1.52 

KNO3 

2 

108.83 

34.31 

105.44 

27.97 

6.35 

KNO3 

1 

138.18 

63.66 

129.79 

52.32 

11.34 

NH4NO3 

8 

84.83 

10.31 

86.52 

9.05 

1.27 

NH4NO8 

2 

114.10 

39.59 

111.81 

34  .  33 

5.25 

Mg(N03)2 

8 

87.01 

12.49 

87.52 

10.05 

2.44 

Mg(N03)2 

2 

116.62 

41.11 

109.53 

32.06 

9.05 

Mg(N03)2 

1 

140.45 

65.94 

128.26 

50.79 

15.15 

Ca(N03)2 

8 

85.28 

10.77 

86.00 

8.53 

2.24 

Ca(N03)2 

2 

109.01 

34.49 

104  .  34 

26.87 

7.62 

Ca(N03)2 

1 

125.69 

51.17 

115.68 

38.20 

12.97 

Sr(N03)2 

8 

84.00 

9.48 

85.01 

7.54 

1.95 

Sr(N03)2 

o 

104.46 

29.94 

99.74 

22.27 

7.67 

Sr(N03)2 

1 

115.42 

41.23 

106.92 

29.44 

11.78 

KC1 

8 

84.81 

10.29 

87.01 

99.54 

0.75 

KC1 

2 

115.09 

40.57 

113.72 

36.25 

4.33 

KC1 

1 

155.72 

81.20 

149.74 

72.27 

8.93 

TABLE  103. 

0.5  molar  for  NaNO3;  0.310  molar  for  Ca(NO3)2. 


Added 
salt. 

V 

s 

A.s 

s' 

A*' 

As  -A-?' 

NaNO3 

8 

50.78 

8.43 

51.78 

7.67 

0.75 

NaNOj 

2 

74.56 

32.21 

73.73 

29.63 

2.58 

NaNO3 

1 

101.50 

59.15 

98.06 

53.96 

5.19 

KNO3 

8 

52.68 

10.33 

53.67 

9.57 

0.77 

KNO3 

2 

81.80 

39.45 

80.72 

36.62 

2.83 

KNO3 

1 

115.64 

73.29 

111.90 

67.80 

5.50 

NH4N03 

8 

53.58 

11.23 

54.44 

10.33 

0.89 

NH4N03 

2 

86.60 

44.25 

85.36 

41.26 

3.00 

NH4NO3 

1 

126.48 

84.13 

122.66 

78.56 

5.57 

Mg(NO3)2 

8 

57.33 

14.98 

57.83 

13.72 

1.25 

Mg(N03)2 

2 

94.39 

52.04 

91.71 

47.60 

4.44 

Mg(NO3)2 

1 

126.18 

83.83 

120.63 

76.53 

7.30 

CaNO3)2 

8 

56.12 

13.77 

56.72 

12.62 

1.15 

Ca(N03)2 

2 

88.13 

45  .  78 

86.46 

42.36 

3.42 

Ca(N03)2 

1 

112.60 

70.25 

108.49 

64.39 

5.87 

Sr(N03)2 

8 

55.13 

12.78 

56.01 

11.91 

0.87 

Sr(N03)2 

2 

83.23 

40.88 

81.96 

37  .  85 

3.03 

Sr(N03)2 

1 

103.27 

60.92 

99  .  05 

54.95 

5.97 

KC1 

8 

53.94 

11.59 

55.14 

1  1  .  03 

0.55 

KC1 

2 

89.30 

46.95 

88.67 

44.56 

2.39 

KC1 

1 

132.99 

90.64 

130.94 

86.84 

3.81 

The  Dissociatin  Powers  of  Free  and  of  Combined  Water. 

TABLE  104. 
Molar  for  KNO3;  0.698  molar  for  Ca(NO3)2. 


127 


Added 
salt. 

V 

s 

As 

s' 

As' 

s-As' 

NaNO3 

8 

97.84 

7.09 

84.69 

5.80 

1.29 

NaNO3 

2 

116.64 

25.89 

98.83 

20.94 

4.95 

NaNO3 

1 

138.90 

48.15 

117.73 

38.84 

9.31 

KN03 

8 

100.08 

9.33 

86.26 

7.34 

1.95 

KN03 

2 

125.02 

34.26 

106.61 

27.83 

6.43 

KNO3 

1 

155.41 

64.66 

131.04 

52.15 

12.51 

Sr(N03)2 

8 

99.75 

9.00 

86.00 

7.11 

1.89 

Sr(N03)2 

2 

117.89 

27.14 

100.25 

21.37 

5.77 

Sr(N03)2 

1 

128  .  86 

38.11 

108.09 

19.20 

8.91 

KC1 

8 

102.38 

11.63 

88.13 

9.25 

2.38 

KC1. 

2 

136.72 

45.97 

115.05 

36.16 

9.81 

KC1 

1 

180.38 

89.63 

150.27 

71.38 

18.25 

NaCl 

8 

100.08 

9.33 

86.08 

7.20 

2.14 

NaCl 

2 

125.94 

35.20 

107.22 

28.34 

6.86 

Nad 

1 

156.15 

65.41 

131.75 

52.86 

12.54 

DISCUSSION  OF  RESULTS. 

The  conductivity  values  to  be  found  in  the  second  and  fourth 
columns  of  tables  100  to  104  are  not  the  sums  of  the  specific  conduc- 
tivities of  the  two  salts  present  in  each  case,  but  are  less  than  this 
sum  because  of  the  common  ion  effect.  Furthermore,  since  the  two 
solutions  in  any  given  case  contain  the  same  number  of  anions,  the 
added  salt  not  being  considered,  the  driving  back  of  the  dissociation 
of  the  added  salt  by  these  anions,  other  things  being  equal,  would 
be  the  same.  An  inspection  of  the  tables  will  show  that  for  every 
pair  of  solutions  studied  this  suppression  is  more  pronounced  in  the 
hydrated  solutions.  Or,  stating  it  in  another  way,  the  increase  in 
conductivity  caused  by  the  addition  of  the  same  amount  of  added  salt 
is  always  greater  in  the  non-hydrated  solutions.  This  means  that  the 
added  salts  dissociate  more  in  the  last-named  solutions  than  in  the 
comparable  isohydric  solutions  of  hydrated  salts. 

A  closer  inspection  of  the  tables  reveals  the  fact  that  the  driving 
back  of  the  ionization  of  the  hydrated  salts  added  is  much  greater  than 
the  driving  back  of  comparable  quantities  of  non-hydrated  salts  in 
both  isohydric  solutions  of  every  pair  studied.  A  comparison  of  tables 
102  and  103  will  show  that  for  any  one  added  salt  the  difference 
in  the  increases  of  conductivity  in  table  102  is  approximately  double 
the  corresponding  difference  in  table  103.  Finally,  a  few  salts  were 
added  which  do  not  have  ions  in  common,  and  these  behaved  in 
somewhat  the  same  manner  as  the  other  added  salts,  though  the  results 
are  somewhat  irregular.  How  can  all  these  facts  be  explained? 


128  Studies  on  Solution. 

A  tentative  explanation  based  upon  these  somewhat  limited  observa- 
tions is  offered  which  is  by  no  means  final.  When  a  salt  is  added  to 
water  or  to  the  solution  of  another  added  salt,  the  added  salt  is  dis- 
sociated by  the  water  present.  It  is  believed  that  combined  water— 
i.  e.,  water  of  hydra tion — in  the  solution  of  hydrated  salts  possesses  less 
ionizing  power  than  the  uncombined  water,  in  which  case  the  salts 
added  would  be  less  dissociated.  And  further,  this  effect  would  be 
greater  the  greater  the  concentration,  since  more  combined  water 
would  then  be  present.  The  hydrated  salts  used  as  added  salts  are  less 
dissociated  than  the  other  added  salts  because  water  of  hydration  now 
exists  in  both  of  any  pair  of  solutions.  However,  the  dissociation 
is  always  less  in  the  case  of  the  hydrated  salt  of  any  pair  because  of 
the  less  dissociating  power  of  the  water  of  hydration  already  present 
in  that  solution. 

These  results  and  conclusions  which  follow  are  to  be  regarded  as 
preliminary.  The  nitrates  and  chlorides  have  been  used  and  not  the 
sulphates,  principally  because  they  are  less  liable  to  form  double  salts. 
But  in  the  concentrated  solutions  it  can  not  be  said  with  certainty 
that  no  complexes  were  present. 

Values  for  the  degree  of  dissociation  based  upon  the  equation 

u, 

a  —  —    are  somewhat  open  to  doubt.1    The  conductivity  of  a  solution 

Moo 

(apart  from  experimental  errors)  is  dependent  to  a  greater  or  less 
extent  upon  the  viscosity  of  the  medium  and  the  migration  velocity 
of  the  ions.  The  latest  relation  between  viscosity  and  conductivity 
has  been  deduced  by  Washburn  and  Clark.2  Unfortunately  this  is  of 
little  value  in  applying  a  viscosity  correction,  since  one  of  the  factors 
is  dependent  upon  the  nature  of  the  medium  and  there  is  at  present  no 
means  of  evaluating  it  for  solutions  of  strong  electrolytes. 

Considering  the  speed  of  the  ions,  no  quantitative  correction  can 
be  made.  It  will  be  noticed  that  normal  solutions  of  sodium  and  potas- 
sium nitrates  have  been  paired  with  calcium  nitrate  solutions.  The 
migration  velocity  of  potassium  is  greater,  while  that  of  sodium  is  less 
than  the  migration  velocity  of  \  calcium,  yet  this  fact  hardly  affects 
the  results.  Lewis3  has  recently  held  that  the  speed  of  ions  actually 
increases  rather  than  decreases  with  increasing  concentration,  and  so 
the  degree  of  dissociation  based  upon  the  conductance  ratio  is  always 
too  high.  The  evidence  either  way,  however,  is  not  conclusive. 

From  his  extensive  work  upon  dielectric  properties  of  solutions, 
Walden4  concludes  that  the  presence  of  salts  in  solutions  increases  the 
ionizing  power  of  the  solvent.  With  this  granted,  the  hydrated  salts 
may  be  said  to  alter  the  dielectric  constant  differently  from  the  non- 

KJourn.  Amer.  Chem.  Soc.,  38,  788  (1916).  *Ibid.,  37,  1043  (1915). 

.,  38  (1916).  "Zeit.  physik.  Chem.,  55,  683  (1906). 


The  Dissociating  Powers  of  Free  and  of  Combined  Water.  129 

hydrated  salts,  since  we  believe  their  ionizing  powers  to  be  different. 
This  does  not  mean  that  the  combined  water  is  more  or  less  associated, 
for  while  the  dissociating  solvents  with  highest  dielectric  constants  are 
usually  most  highly  associated,  the  principle  is  not  without  exception. 
The  results  presented  here  are  relative.  It  would  be  interesting  to 
make  a  further  study  along  the  same  lines,  but  eliminating  any  influ- 
ence of  viscosity  by  the  use  of  some  indifferent  substance  such  as 
sucrose.  Then,  too,  a  determination  of  the  dielectric  constants  of 
the  various  pairs  of  solutions  by  one  of  the  methods  suggested  by 
Drude1  or  Smale2  should  lead  one  to  a  more  definite  statement. 

lWied.  Ann.,  59,  17;  60,  600.        2/6w*.t  57,  215;  60,  625. 


CHAPTER  VI. 

THE  DIFFERENCE  IN  CHEMICAL  ACTIVITY  OF  FREE  AND  SEMI-COM- 
BINED WATER  AS  ILLUSTRATED  BY  THE  EFFECT  OF  NEUTRAL 
SALTS  ON  THE  HYDROLYSIS  OF  ACETIC  ANHYDRIDE.1 


BY  GERALD  C.  CONNOLLY. 


INTRODUCTION 
HYDROLYSIS. 

The  term  "hydrolysis"  is  applied  to  a  number  of  chemical  reactions 
in  which  there  is  first  the  addition  of  water  to  a  complex,  and  then 
the  decomposition  of  the  product  into  simpler  substances.  From  this 
definition  it  is  evident  that  the  reactions  included  under  hydrolysis  are 
numerous  and  varied.  There  are,  in  general,  four  main  divisions  of 
hydrolysis: 

(1)  Hydrolysis  of  metallic  salts. 

(2)  Hydrolysis  of  esters  and  closely  associated  substances,  such  as 

amides,  nitriles,  acid  chlorides,  acid  anhydrides,  etc. 

(3)  Hydrolysis  of  complex  carbohydrates  and  glucosides. 

(4)  Hydrolysis  of  polypeptides  and  proteins. 

In  this  discussion  we  will  confine  ourselves  almost  entirely  to  the 
first  two  divisions,  for  these  are  the  only  forms  of  hydrolysis  which 
come  within  the  scope  of  this  investigation. 

HYDROLYSIS  OF  ACETIC  ANHYDRIDE. 

The  hydrolysis  of  acetic  anhydride  has  been  studied  by  several  inves- 
tigators with  varying  degrees  of  success.  The  term  "hydrolysis  of 
acetic  anhydride"  is  used  here  in  preference  to  the  term  "hydration 
of  acetic  anhydride"  used  by  other  investigators,  since  it  is  more  in 
accordance  with  the  definition  of  hydrolysis  previously  stated.  The 
work  of  previous  investigators  has  been  carefully  reviewed  in  a  prelim- 
inary paper  on  this  subject.  Therefore  it  need  only  be  referred  to  here 
when  bearing  directly  on  the  present  work. 

Menschutkin  and  Vasilieff,2  in  studying  the  decomposition  of  acetic 
anhydride  by  water,  found  that  with  a  mixture  of  equal  portions  of 
acetic  anhydride  and  water  at  19°  only  about  one-half  the  anhydride 
was  hydrolyzed  at  the  end  of  6  hours,  and  1 1  days  were  necessary  for 
complete  hydrolysis.  In  table  105,  taken  from  their  work,  a  com- 
parison is  made  between  the  velocities  of  decomposition  of  acetic 

*See  preliminary  paper  on  this  subject  in  Carnegie  Inst.  Wash.  Pub,  No.  230. 
2Jour.  Russ.  Phys.  Chem.  Soc.,  21,  188  (1889). 

131 


132 


Studies  on  Solution. 


anhydride,  acetamide,  and  ethyl  acetate  by  1  gram-equivalent  of 
water  at  100°  under  the  same  conditions.  The  experiments  were 
carried  out  in  the  presence  of  acetic  acid. 


TABLE  105.1 


Substance  

Acet.  Anhyd. 
+  1H20 

Acetamide. 
+  1H20 

Ethyl  Acetate. 
+1H20 

Acetic  acid  added 

Per  cent. 
11.86 

Per  cent. 
15.85 

Per  cent. 
11.45 

Decomposition: 

1  inin. 

25.  6S 

4.51 

0.2 

11 

83.9 

4.64 

.5 

61 

98.5 

4.94 

.87 

121 

99.5 

5.82 

.99 

181 

99.7 

6.41 

... 

TABLE  106. — Hydrolysis  of  Acetic 
Anhydride  by  Water. 


The  acetic  anhydride  was  almost  entirely  decomposed  at  the  end 
of  1  hour,  while  the  decomposition  of  the  acetamide  was  slight  and  that 
of  the  ethyl  acetate  had  hardly  begun. 

A.  and  L.  Lumiere  and  Barbier  showed  that  when  acetic  anhydride  is 
dissolved  in  water  the  solution  possesses  practically  all  the  properties 
of  acetic  anhydride  itself,  but  that  if 
more  than  12  parts  of  the  anhydride  are 
used  solution  is  incomplete.  Table  106 
shows  their  results  with  5  and  10  per 
cent  solutions  of  the  anhydride  in  cold 
water.  Aliquot  parts  of  each  solution 
were  withdrawn  at  10-minute  intervals 
and  added  to  a  known  slight  excess  of 
aniline,  which  reacted  quantitatively 
with  the  nonhydrolyzed  portion  of  the 
acetic  anhydride,  forming  acetanilid  and 
an  equivalent  of  acetic  acid.  Subse- 
quent titration  with  a  normal  solution  of 
sodium  by  dioxide  gave  the  total  acid 
present,  from  which  the  degree  of  hydro- 
lysis of  the  acetic  anhydride  was  calcu- 
lated. From  their  results  it  can  be  seen 
that  the  rate  of  hydrolysis  is  fairly  rapid 
at  first  and  then  gradually  decreases.  It 
is  the  more  rapid  the  greater  the  initial 
dilution  of  the  anhydride  and  the  higher  the  temperature. 

Alcoholic  solutions  of  the  anhydride  were  also  prepared,  and  it  was 
found  that  when  molecular  proportions  were  used,  esterification  was 
incomplete,  even  after  a  month. 

lBull.  Soc.  Chim.  (Ill)  33,  783  (1905);  35,  625  (1906). 


5  per  cent 

10  per  cent 

Solution. 

Solution. 

Time 

15° 

0° 

15° 

0° 

0 

9.2 

4.6 

11.5 

9.8 

10 

52.5 

35.0 

58.2 

34.6 

20 

74.2 

48.4 

71.0 

51.1 

30 

89.7 

60.8 

78.9 

60.0 

40 

95.7 

69.0 

86.6 

67.0 

50 

100.0 

76.2 

91.7 

73.3 

60 

80.4 

93.3 

77.9 

70 

85.5 

94.6 

81.5 

80 

89.6 

96.4 

85.1 

90 

93.8 

97.9 

88.9 

100 

96.9 

100.0 

92.8 

110 

.... 

100.0 

94.8 

120 

95.8 

140 

.  .  .  . 

98.5 

160 

100.0 

Chemical  Activity  of  Free  and  Semi-Combined  Water.  133 

Orton  and  M.  Jones,  in  addition  to  studying  the  velocity  of  hydrolysis 
of  acetic  anhydride  in  acetic  acid  and  water,  investigated  the  effect 
of  catalysts.  It  was  found  that  acids  are  powerful  catalysts  of  the 
hydrolysis.  The  effect  is  most  noticeable  in  media  containing  but 
little  water,  and  diminishes  as  the  proportion  of  the  water  increases, 
being  least  obvious  in  pure  water.  The  value  of  the  velocity  factor  is 
a  linear  function  of  the  concentration  of  the  acid.  Alkalis  and  hydro- 
lyzed  salts  were  also  found  to  act  as  strong  catalysts  of  the  hydrolysis 
in  aqueous  solutions.  The  following  equations  were  given  to  represent 
the  mechanism  of  the  hydrolysis: 

(I)  AC2O+H2O  =  2AcOH 
(II)  AC20+H2O+H+  =  2AcOH+H+ 

(III)  AC2O+H2O+HX=2AcOH+HX 

(IV)  AC2O+H20  +  OH=2AcOH+OH 

Any  one  of  the  four  forms  could  predominate,  according  to  the  con- 
ditions, medium,  etc.  In  aqueous  solutions  the  choice  lies  between 

(I),  (II),  and  (IV). 

HYDROLYSIS  OF  SALTS. 

It  is  a  well-known  fact  that  certain  salts,  even  though  they  contain 
the  strictly  equivalent  quantities  of  acid  and  base  required  for  "neu- 
trality," when  dissolved  in  water  are  not  neutral  to  indicators,  but 
react  either  acid  or  alkaline.  This  was  first  noticed  by  H.  Rose,  in 
working  with  certain  basic  salts,  but  was  not  explained  satisfactorily 
until  Arrhenius  proposed  his  theory  of  electrolytic  dissociation.  In  the 
light  of  this  theory  acidity  is  due  to  the  presence  of  an  excess  of  hydro- 
gen ions,  while  alkalinity  is  due  to  the  presence  of  an  excess  of  hydroxyl 
ions.  These  ions  can  not  be  accounted  for  by  the  salts  themselves; 
therefore  they  must  be  accounted  for  by  the  water. 

Water  must  contain  both  hydrogen  and  hydroxyl  ions.  The  ioniza- 
tion  constant  of  water  can  be  calculated  by  the  equation 

H+XOH- 
H20 

Since  the  active  mass  of  the  nonionized  water  is  so  great  in  comparison 
with  the  active  mass  of  the  ions,  it  may  be  considered  constant.  We 
then  have  H+  XOH~  =  A;  H2O,  the  value  of  &  being  1.2X10-14  at  25°. 
This  ionization  is  the  same  in  all  aqueous  solutions.  The  value 
&H2o>  however,  increases  with  rise  in  temperature.  This  increase  is 
most  probably  due  to  the  breaking  down  of  the  associated  molecules 
into  the  simpler  ones,  which  are  more  easily  dissociated.  Pure  water 
contains  an  equal  number  of  hydrogen  and  hydroxyl  ions,  and  there- 
fore must  react  neutral.  Furthermore,  this  relation  holds  for  any 
neutral  solution.  To  be  acidic,  a  solution  must  contain  an  excess  of 


134  Studies  an  Solution. 

hydrogen  ions;  to  be  basic,  an  excess  of  hydroxyl  ions.  To  determine 
whether  a  solution  is  neutral  or  not,  we  therefore  make  use  of  indicators, 
such  as  litmus,  methyl  orange,  phenolphthalein,  which  give  evidence 
by  their  color  changes. 

When  a  normal  salt  is  dissolved  in  water,  partial  hydrolysis  takes 
place,  yielding  free  acid  and  free  base.  Whether  the  solution  will 
react  acid  or  alkaline  will  depend  on  the  degree  of  dissociation  of  these 
products  of  hydrolysis.  It  follows,  therefore,  that  there  are  four  types 
of  salts  which  may  undergo  hydrolysis:  (1)  salts  derived  from  strong 
acids  and  strong  bases;  (2)  salts  of  weak  acids  and  strong  bases; 
(3)  salts  of  strong  acids  and  weak  bases;  (4)  salts  of  weak  acids  and 
weak  bases.  All  salts  except  those  of  the  first  type  are  hydrolyzed  to 
a  considerable  extent,  due  to  the  small  degree  of  dissociation  of  one  or  of 
both  of  the  products  of  hydrolysis.  Salts  of  strong  acids  and  strong 
bases  under  ordinary  conditions  do  not  undergo  hydrolysis. 

The  determination  of  the  degree  of  hydrolysis  is  not  accomplished 
without  difficulty.  The  free  acid  or  base  can  not  be  directly  titrated 
with  a  standard  solution,  for  equilibrium  would  be  destroyed  at  once 
and  neutrality  would  be  reached  only  when  the  salt  was  completely 
decomposed.  A  method  must  then  be  employed  which  will  not  destroy 
the  hydrolytic  equilibrium.  The  methods  most  generally  used  are:1 
(1)  the  determination  of  the  velocity  constant  for  the  hydrolysis  of  an 
ester,  for  this  is  proportional  to  the  amount  of  free  acid  or  alkali 
present;  (2)  the  determination  of  the  rate  of  inversion  of  cane  sugar; 

(3)  the  determination  of  the  electrical  conductivity  of  the  solution; 

(4)  the  determination  of  the  coefficient  of  distribution  between  two 
solvents.    There  are  also  many  other  methods  of  more  or  less  limited 
applicability. 

Only  those  salts  were  used  in  this  investigation  which  were  proved 
by  the  above  methods  to  be  nonhydrolyzed.  For  these  salts  the  values 
of  k  calculated  according  to  the  equation 

(Salt)         _     k 

(Acid)  X  (Base)  ~A:H2o 

are  so  small  that  they  need  not  be  taken  into  account.  The  salts  were 
further  tested  according  to  an  observation  made  by  Salm,2  that  salts 
which  give  no  reaction  with  litmus  have  a  concentration  of  H+  and 
OH"  ions  less  than  1 X 10"6,  a  value  so  small  that  it  is  negligible. 

NEUTRAL  SALT  ACTION. 

In  a  discussion  of  neutral  salt  action  one  must  distinguish  clearly 
between  the  effect  produced  by  a  neutral  salt  on  the  catalytic  activity 
of  an  acid  (or  alkali),  and  the  effect  of  the  neutral  salt  on  hydrolysis 
by  water  alone.  It  is  the  latter  effect  in  which  we  are  most  interested 

1R.  C.  Farmer:  B.  A.  Reports,  240  (1901).  2Zcit,  physik.  Chem.  57,  471  (1907). 


Chemical  Activity  of  Free  and  Semi-Combined  Water.  135 

in  this  investigation,  although  the  former  is  what  is  generally  under- 
stood by  the  term  "neutral  salt  action." 

EFFECT  OF  NEUTRAL  SALTS  ON  THE  CATALYTIC  ACTIVITY  OF  ACIDS. 

It  was  early  found1  that  the  addition  of  a  substance  which  is  largely 
ionized  in  aqueous  solution  alters  the  rate  of  hydrolysis  of  esters  or 
of  carbohydrates  by  strong  acids.  This  has  been  proved  by  the  addi- 
tion of  metallic  chlorides  to  mixtures  in  which  hydrochloric  acid  is  the 
catalyst,  the  addition  of  bromides  to  hydrobromic  acid,  and  of  nitrates 
to  nitric  acid.  Those  chlorides  which  are  highly  dissociated  have 
much  the  same  effect,  while  a  salt  like  mercuric  chloride,  which  is 
only  partially  ionized,  has  a  much  feebler  action.  Non-electrolytes, 
such  as  the  alcohols  of  sugars,  have  but  little  effect  on  the  hydrolytic 
activity  of  the  hydrogen  ions. 

The  action  of  the  neutral  salt  is  not  always  to  accelerate  the  hydroly- 
sis; often  there  is  a  retardation.  There  are  also  well-defined  differ- 
ences between  the  influence  of  neutral  salts  on  the  rate  of  inversion  of 
cane  sugar  in  the  presence  of  acids  and  their  influence  in  the  catalytic 
hydrolysis  of  esters.  The  velocity  of  the  inversion  of  cane  sugar  is 
increased  to  a  much  greater  extent  by  the  addition  of  certain  concen- 
trations of  salts  than  is  the  velocity  of  the  hydrolysis  of  esters. 

Neutral  salts  have  in  general  a  retarding  effect  upon  the  hydrolysis 
of  esters  and  amides  by  alkalis.  Senter,2  however,  found  that  the 
hydrolysis  of  sodium  chloroacetate  by  sodium  hydroxide  was  greatly 
accelerated  by  the  presence  of  neutral  salts.  It  has  been  shown  that 
neutral  salt  action  is  independent  of  the  concentration  of  the  compound 
hydrolyzed,  is  proportionally  greater  the  more  dilute  the  acid  solution, 
is  not  greatly  influenced  by  temperature  or  pressure,  and  is  independent 
of  the  nature  of  the  acid  employed  as  catalyst. 

In  addition,  Poma3  has  determined  that  the  intensity  of  the  action 
developed  by  neutral  salts  bears  a  strict  relation  to  the  chemical  nature 
of  the  ions  of  the  salts  and  diminishes  in  passing  from  chlorides  to 
bromides  to  nitrates  to  iodides,  in  succession;  that  it  is  independent  of 
the  chemical  nature  of  the  cations;  and,  finally,  that  it  seems  to  be  pro- 
portional, not  to  the  concentration  of  the  salt  in  the  solution,  but  to 
the  concentration  of  the  ions. 

EFFECT  OF  NEUTRAL  SALTS  ON  HYDROLYSIS  BY  WATER  ALONE. 

Probably  the  first  work  done  on  neutral  salt  action  in  the  absence  of 
an  acid  was  by  Smith,4  who  investigated  the  effect  of  neutral  salts  on 
the  rate  of  inversion  of  cane  sugar.  He  found  that  salts  of  weak  acids 
had  almost  no  effect,  while  potassium  chloride  and  sodium  sulphate, 
the  more  nearly  neutral  salts,  had  considerable  effect. 

Mourn,  prakt.  Chem.  85, 321, 401  (1862).      3Medd.  K.Vetenskapsakad.  Nobelinst.,  2,  No.  11, 1-28. 
2Journ.  Chem.  Soc.  91,  473  (1907).  4Zeit.  physik.  Chem.  25,  144  (1898). 


136  Studies  on  Solution. 

Senter  showed  that  neutral  salts  have  practically  no  effect  on  the 
decomposition  of  sodium  chloroacetate  by  water 

Kellogg1  studied  the  effect  of  the  neutral  salts,  potassium  chloride, 
potassium  bromide,  and  potassium  iodide  on  the  velocity  of  the  hydro- 
lysis of  ethyl  acetate.  The  reactions  were  carried  out  in  sealed  tubes 
at  100°,  using  a  fixed  quantity  of  ester  and  varying  concentrations  of 
the  salt  solution.  The  results  obtained  show  that  the  specific  influence 
of  salts  is  greater  in  somewhat  dilute  solutions.  As  the  concentration 
is  increased,  the  effect  gradually  becomes  less  until  it  reaches  zero,  and 
then  becomes  negative  in  character;  for  example,  a  4-normal  solution  of 
potassium  chloride  hydrolyzes  the  ester  more  slowly  than  pure  water 
itself.  Kellogg  found  a  decrease  in  the  accelerating  power  from 
chloride  to  bromide  to  iodide,  which  is  in  reverse  order  to  their  stability. 

Henderson  and  Kellogg2  continued  the  investigation,  using  the 
chlorides  of  sodium,  lithium,  calcium,  strontium,  and  barium,  and  the 
chloride  and  iodide  of  cadmium.  They  carried  out  the  work  under  the 
same  conditions  as  before  and  also  measured  the  conductivities  and 
viscosities  of  the  solutions  at  the  concentrations  and  temperatures 
employed  in  the  experiments;  and  from  these  calculated  the  degree 
of  ionization.  They  found  that  the  salts  which  produce  the  greatest 
effect  are  those  which  are  the  least  ionized.  The  accelerating  effect 
of  lithium  chloride  is  greater  than  that  of  sodium  chloride,  although  the 
degree  of  ionization  of  the  former  is  less,  while  the  chlorides  of  calcium, 
barium,  and  strontium  have  a  greater  effect  than  either  sodium  chloride 
or  potassium  chloride,  although  they  too  are  less  ionized.  Cadmium 
chloride,  the  least  ionized  of  all  the  chlorides  studied,  produced  the 
greatest  effect,  due  probably  to  the  hydrolysis  of  the  salt.  Henderson 
and  Kellogg  concluded  that  the  effect  produced  by  a  neutral  salt  on  the 
hydrolysis  of  ethyl  acetate  is  due  to  a  specific  influence  on  the  non- 
ionized  portion  of  the  salt,  rather  than  to  any  function  of  the  ions. 

There  have  been  several  suggestions  put  forward  to  explain  neutral 
salt  action.  Arrhenius3  proposed  that  the  salts  may  affect  the  sub- 
stance which  is  being  hydrolyzed;  that  there  may  be  present  in  the 
solution  an  equilibrium  between  an  active  and  an  inactive  form  of 
the  substrate,  and  that  this  equilibrium  may  be  altered  through  changes 
of  temperature  or  ionic  concentration.  Armstrong  and  Caldwell 
concluded  that  the  salts  act  by  removing  part  of  the  water  in  the  form 
of  definite  hydrated  compounds,  and  in  this  manner  increase  the 
concentration  of  the  reacting  substance.  Stieglitz  explained  salt 
effect  in  general  by  the  theory  that  the  presence  of  salts  in  the  solution 
increases  the  dielectric  constant,  or  at  any  rate  the  ionizing  power  of 
the  solvent.  All  of  these  theories  are  plausible,  but  it  is  highly  improb- 
able that  neutral  salt  action  is  due  to  any  one  cause  exclusively. 

lJourn.  Amer.  Chem.  Soc.  31,  403,  886  (1909).        3Zeit.  phys.  Chem.  4,  226  (1889). 
35,  396  (1913). 


Chemical  Activity  of  Free  and  Semi-Combined  Water.  137 

STATEMENT  OF  THE  PROBLEM. 

The  object  of  this  investigation  and  the  methods  used  were  fully 
outlined  in  the  preliminary  paper.  However,  in  order  that  the  com- 
pleted work  may  be  more  readily  understood,  they  are  repeated  here  in 
some  detail. 

The  studies  on  the  absorption  spectra  of  solutions  carried  out 
in  this  laboratory  by  Anderson,  Strong,  Guy,  Shaeffer,  and  others  led 
to  the  conclusion  that  a  marked  physical  difference  exists  between  free 
and  combined  water.  It  seemed  desirable,  therefore,  to  determine 
whether  a  similar  chemical  difference  was  to  be  found.  With  this  in 
view,  Holmes  and  Jones1  took  up  a  study  of  the  action  of  strongly  hy- 
drated  salts  and  slightly  hydrated  salts  on  the  hydrolysis  of  methyl 
acetate  and  methyl  formate.  The  method  used  consisted  in  measuring 
the  velocity  of  hydrolysis  of  the  ester  by  pure  water  and  by  solutions 
of  slightly  and  strongly  hydrated  salts.  The  solutions  were  prepared 
in  such  a  way  that  the  amount  of  water  in  each  was  the  same  and  was 
equal  to  the  amount  of  pure  water  employed.  Taking  into  account  the 
hydrolysis  of  the  strongly  hydrated  salts,  they  found  that  these  salts 
hydrolyzed  the  ester  much  more  rapidly  than  pure  water  itself. 

The  reaction  studied  by  Holmes  and  Jones  was  a  very  slow  one  and 
indicated  that  combined  water  has  greater  activity  than  free  water. 
We  wished  to  investigate  the  same  problem,  using  a  reaction  that  pro- 
ceeded much  more  rapidly;  therefore  we  chose  the  reaction  involving 
the  conversion  of  acetic  anhydride  into  acetic  acid. 

EXPERIMENTAL. 
PURIFICATION  OF  ACETIC  ANHYDRIDE. 

Pure  acetic  anhydride  was  necessary  for  the  work.  The  physical 
properties  as  described  in  the  literature  vary  greatly.  The  boiling- 
points  given  range  anywhere  from  135°  to  140°  at  760  mm.  pressure. 
The  densities  given  vary  between  1.07  and  1.09.  From  this  it  can  be 
seen  that  it  was  impossible  to  test  its  purity  by  the  ordinary  simple 
means.  Acetic  acid  is  the  impurity  most  likely  to  be  present  in  the 
anhydride,  and  is  very  difficult  to  detect  if  only  small  amounts  are 
present.  0.51  gram  of  pure  acetic  anhydride,  when  completely  hydro- 
lized,  is  equivalent  to  100  c.c.  N/10  solution  of  sodium  hydroxide,  while 
the  same  weight  of  a  mixture  containing  1  per  cent  of  acetic  acid  is 
equivalent  to  99.85  c.c.  This  is  within  the  experimental  error. 

Methods  of  finding  the  actual  percentage  of  acetic  acid  and  anhydride 
in  a  mixture  have  been  given  by  Pickering,2  Menschutkin  and  Vasilieff  ,3 
Treadwell,4  Edwards  and  Orton,5  and  Orton  and  Jones.6  Pickering 

Carnegie  Inat.  Wash.  Pub.  No.  230  (1915),  Analytical  Chemistry,  1914,  vol.  u. 

'Journ.  Chem.  Soc.  63,  1000  (1893).  Mourn.  Chem.  Soc.  99,  1181  (1911). 

Uourn.  Russ.  Phys.  Chem.  Soc.  21,  190  (1889).       'Ibid.,  101,  1720  (1912). 


138  Studies  on  Solution. 

determined  the  freezing-points  of  the  solutions  of  anhydride  and  water, 
and  compared  them  with  the  freezing-points  of  known  concentrations 
of  acetic  acid.  Menschutkin  and  Vasilieff  treat  with  aniline  and  water, 
and  determine  the  acidity  after  the  reaction 

C6H5NH2+ (CH3CO)2O  =  CeHsNHCOCHs+CHaCOOH 

has  taken  place.  Treadwell  recommends  treatment  with  barium- 
hydroxide  solution  and  titration  of  the  excess  of  the  latter,  while 
Edwards  and  Orton  convert  the  anhydride  into  acetanilid,  the  latter 
into  phenylacetylchloramine,  and  then  determine  the  chloramine  volu- 
metrically. 

The  method  finally  adopted  to  purify  the  acetic  anhydride  was  that 
of  repeated  distillation,  using  a  5-bulb  distilling  head  and  discarding  the 
first  and  last  fractions.  This  gave  an  anhydride  which  distilled  prac- 
tically constant  at  138°  to  139°.  Specific  gravity  determinations,  using 
a  10  c.c.  pycnometer,  gave  a  mean  value  of  1.0852  at  15°/4°.  The 
acetic  anhydride  was  further  tested  by  titrating  weighed  samples  both 
directly  and  by  the  method  advocated  by  Menschutkin  and  Vasilieff. 

PURIFICATION  OF  SALTS. 

Only  the  purest  salts  obtainable  were  used.  They  were  usually 
Kahlbaum  preparations,  although  some  of  other  well-known  firms  were 
used.  These  salts  were  dissolved  in  conductivity  water,  filtered  from 
any  foreign  matter  present,  and  then  recrystallized  one  or  more  times. 

APPARATUS. 

Thermostats. — The  constant-temperature  baths  were  of  the  improved 
form  designed  by  Davis1  of  this  laboratory.  The  thermometers  were 
of  the  differential  Beckmann  type.  They  were  compared  with  a 
standard  thermometer,  which  had  been  calibrated  at  the  Bureau  of 
Standards.  Flasks,  pipettes,  and  burettes  for  measuring  purposes  were 
all  carefully  calibrated  by  weight.  All  bottles  used  (varying  in 
content  from  50  to  6.1  c.c.)  and  all  measuring  flasks  were  of  Jena  glass. 
A  special  apparatus  was  used  for  the  alkali  solution,  to  protect  it  from 
carbon  dioxide  and  water  vapor  in  the  air. 

SOLUTIONS. 

The  water  used  in  the  preparation  of  the  solutions  was  purified  by  the 
method  of  Jones  and  Mackay2  as  modified  by  Schmidt.3  It  had  a  con- 
ductivity at  no  tune  greater  than  2X10"6. 

The  aniline  used  to  combine  with  the  excess  of  acetic  anhydride  was 
the  purest  obtainable.  It  was  further  distilled  as  many  times  as 
necessary  to  remove  all  decomposition  products.  The  slightly  colored 
product  was  then  kept  in  a  cupboard  protected  from  light. 

Carnegie  Inat.  Wash.  Pub.  No.  210  (1914).  3/Wd.,  19,  90  (1897). 

JAmer.  Chem.  Journ.,  17,  83  (1895). 


Chemical  Activity  of  Free  and  Semi-Combined  Water.  139 

The  solutions  of  the  non-hydrated  salts  were  made  up  directly  by 
weight,  while  those  of  the  hydrated  salts  were  analyzed  gravimetrically 
and  diluted  to  the  required  strengths.  The  chlorides  of  barium, 
strontium,  calcium,  and  magnesium  were  determined  as  silver  chloride 
and  the  sulphates  of  sodium  and  magnesium  were  determined  as 
barium  sulphate. 

The  solution  of  sodium  hydroxide  used  in  titrating  the  acetic  acid 
formed  by  the  hydrolysis  of  the  acetic  anhydride  was  made  up  approx- 
imately half-normal,  using  "sodium  hyolroxide  from  alcohol."  It 
was  preserved  in  an  apparatus  protected  from  the  impurities  in  the  air. 
It  was  standardized  by  titration  against  a  solution  of  sulphuric  acid  of 
about  the  same  strength  (0.4115  N).  The  sulphuric  acid  had  been 
standardized  as  barium  sulphate. 

The  indicator  used  was  phenolphthalein,  as  it  gives  the  best  results 
in  titrating  a  weak  acid  with  a  strong  alkali,  the  only  objection  being 
that  it  is  also  sensitive  to  carbonic  acid.  Corallin  had  been  tried,  but 
was  not  so  satisfactory. 

METHOD  OF  PROCEDURE. 

The  method  in  principle  is  a  modification  of  that  of  Menschutkin 
and  Vasilieff,1  and  later  employed  by  A.  and  L.  Lumiere  and  Barbier.2 
In  order  that  the  results  should  be  comparable,  the  amount  of  water 
present  must  be  kept  constant;  therefore  the  specific  gravity  of  the  salt 
solution  was  first  taken,  giving  the  weight  of  1  c.c.  From  analysis,  that 
part  of  the  weight  due  to  the  anhydrous  salt  alone  was  known  for  each 
cubic  centimenter.  This  known  weight  of  salt,  subtracted  from  the 
weight  of  1  c.c.  of  solution,  gave  the  weight  due  to  the  pure  water  alone. 
This,  divided  into  the  weight  of  1  c.c.  of  pure  water  at  that  temperature, 
gave  the  amount  of  solution  in  cubic  centimenters  equivalent  to  1  c.c. 
of  pure  water.  The  amount  of  solution  thus  calculated  was  pipetted 
into  a  250  c.c.  Jena  bottle.  An  equivalent  of  100  c.c.  of  pure  water 
was  taken  in  all  determinations.  The  bottle  was  suspended  in  the 
constant- temperature  bath.  There  was  also  placed  in  the  bath  a 
bottle  containing  the  anhydride  and  a  number  of  small  empty  bottles 
of  50  c.c.  capacity. 

When  all  had  come  to  the  temperature  of  the  bath,  the  bottle  was 
removed  and  5  c.c.  of  the  anhydride  introduced.  Time  was  reckoned 
from  when  the  anhydride  was  first  added.  Solution  took  place 
immediately  on  shaking,  except  in  the  case  of  the  very  concentrated 
solutions.  Aliquot  portions  were  removed  and  placed  in  the  small 
50  c.c.  bottles,  the  whole  being  kept  in  the  bath.  These  small  bottles 
were  removed,  first  every  5,  then  every  10  minutes,  and  a  slight  known 

Carnegie  Inst.  Wash.  Pub.  No.  60,  160  (1907).  -Ibid.,  130  (1910) ;  190  (1910). 


140  Studies  on  Solution. 

excess  of  aniline  added.  On  shaking,  this  combines  with  the  residual 
acetic  anhydride,  precipitating  acetanilid  and  liberating  an  equivalent 
of  acetic  acid.  In  one  bottle  of  each  series  the  reaction  was  allowed  to 
go  to  completion  without  the  addition  of  aniline,  so  as  to  control  the 
results  obtained. 

The  total  amount  of  acetic  acid  was  then  determined  in  the  bottle 
by  titration  with  the  half-normal  solution  of  sodium  hydroxide  in  the 
presence  of  phenolphthalein  as  indicator.  Never  less  than  10  c.c. 
nor  more  than  25  c.c.  of  alkali,  as  measured  in  a  50  c.c.  burette,  was 
required  to  neutralize  the  acetic  acid. 

Two  temperatures,  15°  and  25°,  were  employed.  Only  one  concen- 
tration of  acetic  anhydride  was  used  (approximately  5  per  cent), 
because  if  two  were  employed  the  results  would  not  be  comparable  on 
account  of  volume  changes.  For  the  salts  molar,  half-molar,  and 
quarter-molar  solutions  were  taken  in  all  cases,  and  whenever  possible 
solutions  of  greater  concentration. 

Measurements  of  the  velocity  were  not  taken  for  longer  than  60 
minutes  at  15°  and  40  minutes  at  25°,  for  it  was  found  that  the  hydroly- 
sis of  the  acetic  anhydride  by  water  was  then  practically  complete. 

CALCULATIONS. 

From  the  total  amount  of  acetic  acid,  as  determined  by  titration 
with  the  alkali,  that  due  to  the  water  alone  must  be  calculated.  The 
simple  formula  y  =  2z— x  is  used,  where  y  is  the  amount  of  acetic  acid 
due  to  the  water  alone,  z  is  the  total  amount  of  acetic  acid  measured  by 
titration,  and  x  is  the  total  amount  of  acid  that  can  be  formed  if  all  the 
acetic  anhydride  has  been  hydrolyzed. 

The  results  obtained  for  the  "control"  bottles,  when  substituted  in 
the  formula,  should  give  the  same  values  for  x  and  y,  which  would  be 
equivalent  to  100  per  cent  hydrolysis. 

DATA. 

In  tables  107  to  116  the  concentrations  of  salt  solutions  are  M, 
molar;  M/2,  half-molar,  etc.  Time  is  expressed  in  minutes.  All 
results  are  expressed  in  percentages,  100  per  cent  meaning  complete 
hydrolysis  of  the  acetic  anhydride.  In  each  table  there  is  placed  for 
comparison  a  column  showing  the  percentage  decomposition  of  acetic 
anhydride  by  water  alone. 


Chemical  Activity  of  Free  and  Semi-Combined  Water. 
TABLE  107. 


141 


Time. 

Concentration  —  Potassium  Chloride  at  15°. 

Concentration  —  Potassium  Chloride  at  25°. 

Water. 

3M 

2M 

M 

M/2 

M/4 

Water. 

3M 

2M 

M 

M/2 

M/4 

5 
10 
20 
30 
40 
50 
60 

30.99 
54.15 
78.43 
90.22 
96.87 
98.18 
99.01 

14.68 
30.16 
49.67 
63  67 
73.70 
81.65 
86.54 

21.71 
38.96 
59.93 
73.57 
83.09 
89.24 
92.36 

26.79 
48.85 
69.72 
82.70 
90.76 
94.61 
97.08 

29.2 
50.07 
73.51 
86.53 
93.21 
96.61 
98.13 

31.28 
53.55 
77.33 
89.16 
94.32 
97.48 
98.63 

44.54 
72.76 
93.71 
98.31 
99.53 

24.82 
45.68 
70.82 
84.63 
91.86 

27.58 
55.12 
84.63 
91.50 
94.81 

36.56 
64.98 
87.87 
95.99 
98.13 

42.18 
68.88 
91.08 
96.99 
98.64 

44.14 
71.98 
92.16 
97.59 
99.00 

TABLE  108. 


Time. 

Concentration  —  Sodium  Chloride  at  15°. 

Concentration  —  Sodium  Chloride  at  25°. 

Water. 

4M 

3M 

2M 

M 

M/2 

M/4 

Water. 

4M 

3  M 

2M 

M 

M/2 

M/4 

5 
10 
20 
30 
40 
50 
60 

30.99 
54.15 
78.43 
90.22 
96.87 
98.18 
99.01 

19.24 
24.49 
40.87 
56.04 
64.75 
73.23 
79.02 

21.37 
33.64 
54.07 
67.90 
77.06 
84.53 
88.78 

24.84 
42.71 
65.04 
79.43 
86.47 
90.95 
94.08 

30.44 
52.79 
75.14 
87.42 
92.12 
97.13 
98.21 

32.21 
54.87 
77.88 
89.09 
94.20 
97.70 
98.53 

33.71 
55.98 
79.38 
89.42 
94.65 
97.99 
98.73 

44.54 
72.76 
93.71 
98.31 
99.53 

21.80 
36.85 
60.09 
75.73 
85.90 

28.93 
50.48 
75.62 

87.85 
93.91 

35.44 
60.97 
84.93 
93.45 

97.28 

42.23 
60.07 
90.30 
97.56 
98.75 

44.65 
72.53 
91.90 
97.95 
99.26 

46.91 
73.87 
93.51 
98.57 
99.69 

TABLE  109. 


Time. 

Concentration  —  Calcium  Chloride  at  15°. 

Concentration  —  Calcium  Chloride  at  25°. 

Water. 

4M 

M 

M/2 

M/4 

Water. 

4M 

M 

M/2 

M/4 

5 
10 
20 
30 
40 
50 
60 

30.99 
54.15 
78.43 
90.22 
96.87 
98.18 
99.01 

2.80 
15.60 
41.37 
57.97 
69.51 
77.85 
83.95 

33.98 
55.67 
80.86 
90.45 
95.72 
97.49 
98.90 

34.34 
56.48 
81.08 
91.87 
96.20 
99.13 
99.84 

34.01 
56.58 
81.19 
92.04 
96.96 
98.25 
99.19 

44.54 
72.76 
93.71 
98.31 
99.53 

20.18 
49.93 
78.20 
92.23 
96.16 

48.36 
75.24 
93.76 
99.81 
100.00 

48.61 
76.23 
94.52 
97.94 
99.37 

48.79 
76.81 
94.56 
97.51 
99.65 

TABLE  110. 


Time. 

Concentration  —  Magnesium  Chloride  at  15°. 

Concentration  —  Magnesium  Chloride  at  25°. 

Water. 

4M 

2M 

M 

M/2 

M/4. 

Water. 

4M 

2-M 

M 

M/2 

M/4 

5 
10 
20 
30 
40 
50 
60 

30.99 
54.15 
78.43 
90.22 
96.87 
98.18 
99.01 

1.30 
14.15 
24.80 
52.32 
70.00 
86.61 
89.73 

20.37 
37.30 

58.84 
73.62 
82.22 
88.35 
92.09 

30.01 
49.83 
73.29 
85.01 
92.15 
94.62 
97.76 

30.49 
51.71 
75.81 
88.17 
93.74 
96.96 
98.73 

32.95 
54.64 
78.32 
89.93 
95.09 
97.43 
99.31 

44.54 
72.76 
93.71 
98.31 
99.53 

1.80 
25.36 
73.30 
92.54 
96.73 

29.52 
56.29 
79.97 
91.74 
97.15 

40.01 
69.41 
89.79 
96.16 
98.45 

41.60 
70.89 
92.39 
97.07 

98.84 

43.09 
72.08 
93.31 
97.89 
99.08 

142 


Studies  on  Solution. 


TABLE  111. 


Time. 

Concentration  —  Barium 
Chloride  at  15°. 

Concentration  —  Barium 
Chloride  at  25°. 

Water. 

M 

M/2 

M/4 

Water. 

M 

M/2 

M/4 

5 
10 
20 
30 
40 
50 
60 

30.99 
54.15 
78.43 
90.22 
96.87 
98.18 
99.01 

30.51 
50.56 
74.68 
86.83 
92.96 
97.09 
98.10 

31.49 
54.98 
78.60 
90.30 
95.76 
97.66 
99.10 

34.48 
56.88 
81.05 
91.09 
96.20 
98.10 
99.88 

44.54 
72.76 
93.71 
98.31 
99.53 

39.57 
68.43 
91.25 
97.85 
98.44 

42.04 
73.23 
92.00 
97.99 
98.72 

46.89 
75.90 
93.94 
98.19 
98.85 

TABLE  112. 


Time. 

Concentration  —  Strontium  Chloride 
at  15°. 

Concentration  —  Strontium  Chloride 
at  25°. 

Water. 

2M 

M 

M/2 

M/4 

Water. 

2M 

M 

M/2 

M/4 

5 
10 
20 
30 
40 
50 
60 

30.99 
54.15 
78.43 
90.22 
96.87 
98.18 
99.01 

20.80 
39.43 
63.31 
76.46 
84.93 
89.84 
92.18 

27.44 
48.17 
74.88 
87.19 
94.40 
97.28 
98.42 

32.33 
55.15 
78.86 
90.56 
95.89 
98.00 
99.08 

35.22 
57.00 
80.89 
92.07 
96.30 
98.43 
99.32 

44.54 
72.76 
93.71 
98.31 
99.53 

31.40 
57.58 
84  43 
94.38 
98.19 

41.11 
72.15 
90.86 
96.47 
98.71 

47.17 
74.35 
92.87 
98.79 
99.58 

47.89 
76.01 
94.37 

98.85 
99.64 

TABLE  113. 


Time. 

Concentration.  —  Sodium  Sul- 
phate at  15°. 

Concentration.  —  Sodium  Sul- 
phate at  25°. 

Water. 

M 

M/2 

M/4 

Water. 

M 

M/2 

M/4 

5 
10 
20 
30 
40 
50 
60 

30.99 
54.15 
78.43 
90.22 
96.87 
98.18 
99.01 



38.98 
65.30 
86.15 
94.07 
96.64 
98.32 
99.65 

37.16 
60.57 
83.74 
93.27 
96.43 
98.13 
98.97 

44.54 
72.76 
93.71 
98.31 
99.53 

61.51 
87.56 
98.16 
99.38 
99.83 

54.62 
82.84 
96.95 
99.22 
99.71 

50.52 
79.32 
96.02 
99.16 
99.63 

TABLE  114. 


Time. 

Concentration  —  M  agnesium 
Sulphate  at  15°. 

Concentration  —  Magnesium 
Sulphate  at  25°. 

Water. 

M 

M/2 

M/4 

Water. 

M 

M/2 

M/4 

5 
10 
20 
30 
40 
50 
60 

30.99 
54.15 
78.43 
90.22 
96.87 
98.18 
99.01 

41.62 
66.49 
86.65 
92.71 
94.85 
97.44 
98.37 

41.88 
67.34 
88.45 
96.43 
98.30 
98.83 
99.13 

37.99 
61.09 
83.71 
93.33 
96.96 
98.96 
99.43 

44.54 
72.76 
93.71 
98.31 
99.53 

56.61 
84.26 
95.49 
96.48 
98.13 

50.98 
78.72 
95.82 
98.17 
99.71 

55.23 
80.46 
95.99 
98.29 
99.82 

Chemical  Activity  of  Free  and  Semi-Combined  Water. 
TABLE  115. 


143 


Time. 

Concentration  —  Potassium  Nitrate 
at  15°. 

Concentration  —  Potassium  Nitrate 
at  25°. 

Water. 

2,M 

M 

M/2 

M/4 

Water. 

2M 

M 

M/2 

M/4 

5 
10 
20 
30 
40 
50 
60 

30.99 
54.15 
78.43 
90.22 
96.87 
98.18 
99.01 

21.93 
36.35 
58.29 
71.53 
81.37 
89.93 
92.27 

26.50 
44.79 
64.15 
80.91 
87.11 
93.80 
96.14 

30.59 
51.24 
74.33 
86.18 
92.74 
95.91 
97.43 

31.78 
53.35 
77.15 
88.76 
94.85 
97.20 
98.49 

44.54 
72.76 
93.71 
98.31 
99.53 

34.44 
51.90 
77.03 
88.69 
94.94 

35.56 
54.37 
82.07 
94.58 
97.30 

37.03 
65.93 

88.45 
96.48 
98.60 

41.64 
69.71 
90.92 
98.01 

98.84 

TABLE  116. 


Time. 

Concentration.  —  Sodium  Nitrate 
at  15°. 

Concentration.  —  Sodium  Nitrate 
at  25°. 

Water. 

2M 

M 

M/2 

M/4 

Water. 

2M 

M 

M/2 

M/4 

5 
10 
20 
30 
40 
50 
60 

30.99 
54.15 
78.43 
90.22 
96.87 
98.18 
99.01 

21.69 
36.23 
59.80 
73.51 
81.49 
89.11 
92.47 

26.38 
45.73 
70.35 
81.95 
91.10 
94.38 
97.01 

32.36 
53.12 

77.27 
87.93 
93.61 
97.81 
98.07 

33.66 
54.52 
79.14 
89.11 
94.85 
96.85 
98.37 

44.54 
72.76 
93.71 
98.31 
99.53 

33.14 
54.72 
80.20 
91.87 
96.59 

36.80 
63.93 
86.68 
95.77 
97.89 

41.07 
69.01 
90.58 
97.06 
98.24 

41.64 
69.94 
90.92 
97.54 
98.83 

DISCUSSION  OF  RESULTS. 

There  is  one  difficulty  in  the  study  of  this  problem  that  must  first  be 
pointed  out,  i.  e.,  the  use  of  a  strong  alkali  solution  (half-normal  NaOH) 
with  which  to  titrate  the  acetic  acid  formed.  This  necessarily  intro- 
duces some  error,  since  a  difference  of  0.1  c.c.  in  reading  the  burette 
would  make  a  difference  of  over  1  per  cent.  A  more  dilute  solution  of 
alkali  could  not  be  used,  since  too  large  a  quantity  of  such  a  solution 
would  be  required. 

As  noted  in  the  preliminary  paper  on  this  subject,  the  rate  of  decom- 
position of  the  acetic  anhydride  is  at  first  very  rapid,  being  almost  com- 
plete at  25°  in  5  minutes  and  nearly  three-quarters  complete  at  the  end 
of  10  minutes,  then  gradually  decreasing  as  the  reaction  approaches 
completion.  In  this  respect  the  reaction  differs  from  similar  ones 
studied,  such  as  the  hydrolysis  of  esters,  since  in  these  cases  the  reac- 
tions are  reversible.  Temperature  has  a  marked  accelerating  influence 
on  the  hydrolysis,  the  velocity  of  the  reaction  as  a  whole  and  the 
increase  for  succeeding  intervals  of  time  being  much  greater  at  25°  than 
at  15°. 


144  Chemical  Activity  of  Free  and  Semi-Combined  Water. 

All  the  salts  studied,  with  the  exception  of  sodium  sulphate  and 
perhaps  also  magnesium  sulphate,  have  in  the  case  of  the  greater  con- 
centrations a  retarding  influence  on  the  hydrolysis.  This  retardation 
diminishes  as  the  salt  solution  becomes  more  and  more  dilute.  With 
sodium  sulphate  solutions  the  reverse  is  true — the  more  concentrated 
the  solution  the  greater  is  the  accelerating  effect.  This  is  also  true 
to  a  certain  extent  with  magnesium  sulphate,  although  the  effect  is 
not  so  pronounced. 

In  the  case  of  both  magnesium  salts  studied,  magnesium  chloride 
and  magnesium  sulphate,  it  was  difficult  to  get  clear,  clean-cut  results. 
In  titrating  the  acetic  acid  with  the  alkali  in  the  presence  of  these  salts 
a  good  end-point  could  not  be  reached.  The  color  of  the  indicator, 
phenolphthalein,  appeared  to  be  masked,  especially  in  the  more  con- 
centrated solutions. 

All  the  non-hydrated  salts  studied  have  a  hindering  effect  on  the 
hydrolysis.  The  amount  of  this  hindrance  under  the  same  conditions 
is  practically  the  same  for  the  four  salts  studied,  there  being  at  no  time 
a  variance  of  more  than  a  few  per  cent.  With  the  most  dilute  solutions 
studied,  quarter-molar,  the  results  for  the  decomposition  are  practically 
the  same  as  for  pure  water. 

The  hydrated  salts,  with  the  exception  of  magnesium  chloride,  all 
give  results  for  the  decomposition  greater  than  those  of  the  non- 
hydrated  ones,  while  with  the  more  dilute  solutions  there  is  an  appre- 
ciable acceleration  of  the  hydrolysis  of  the  acetic  anhydride  over  that 
due  to  pure  water  alone.  Sodium  sulphate  and  magnesium  sulphate 
at  all  concentrations  studied  have  a  very  marked  accelerating  effect 
on  the  hydrolysis.  Greater  concentrations  of  these  salts  were  not  used 
for  the  reason  that  they  do  not  mix  with  the  anhydride  at  once  on 
simple  shaking.  Calcium  chloride,  strontium  chloride,  and  barium 
chloride  also  have  an  accelerating  influence  on  the  hydrolysis  in  the 
more  dilute  solution.  Magnesium  chloride  acts  as  do  the  non-hydrated 
salts,  having  a  retarding  influence  at  all  dilutions. 


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